Failure to build ARM template with "optionalModuleNames" experimental feature enabled

[asilverman]

Bicep version

Describe the bug
When I try to compile the following template with a module that has no module name Bicep throws an exception

template.bicep

targetScope = 'managementGroup'

param previousPolicyAssignmentId string
param policyAssignmentRegionsSelected array
param subscriptionId string
param resourceGroupName string
param timestamp string = utcNow()
var checkOldAssignmentName = 'checkOldAssignment_${timestamp}'

resource oldPolicyAssignment 'Microsoft.Authorization/policyAssignments@2023-04-01' existing = {
  name: previousPolicyAssignmentId
}

module checkOldAssignment './checkOldAssignmentModule.bicep' = {
  // name: checkOldAssignmentName
  scope: resourceGroup(subscriptionId, resourceGroupName)
  params: {
    oldPolicyAssignment: oldPolicyAssignment
    scriptName: checkOldAssignmentName
    newLocations: policyAssignmentRegionsSelected
  }
}

resource updatedOldAssigment 'Microsoft.Authorization/policyAssignments@2023-04-01' = {
  name: oldPolicyAssignment.name
  properties: {
    displayName: oldPolicyAssignment.properties.displayName
    enforcementMode: oldPolicyAssignment.properties.enforcementMode
    policyDefinitionId: oldPolicyAssignment.properties.policyDefinitionId
    parameters: oldPolicyAssignment.properties.parameters
    resourceSelectors: checkOldAssignment.outputs.updatedResourceSelectors
  }
}

checkOldAssignmentModule.bicep

param oldPolicyAssignment object
param scriptName string
param newLocations array

var scriptContent = loadTextContent('./checkOldAssignmentScript.ps1', 'utf-8')

resource script 'Microsoft.Resources/deploymentScripts@2023-08-01' = if (!empty(oldPolicyAssignment)) {
  kind: 'AzurePowerShell'
  name: scriptName
  location: resourceGroup().location
  properties: {
    azPowerShellVersion: '6.4'
    environmentVariables: [
      {
        name: 'oldResourceSelectors'
        value: string(oldPolicyAssignment.properties.?resourceSelectors ?? [])
      }
      {
        name: 'newLocations'
        value: string(newLocations)
      }
    ]
    scriptContent: scriptContent
    cleanupPreference: 'Always'
    retentionInterval: 'PT1H'
  }
}

output oldAssignment object = oldPolicyAssignment
output updatedResourceSelectors array = json(script.properties.outputs.text)

bicepconfig.json

{
    "experimentalFeaturesEnabled": {
        "resourceDerivedTypes": true,
        "symbolicNameCodegen": true,
        "optionalModuleNames": true
    }
}

Error:

Error - 4:22:01 PM] Bicep build failed
Internal Error - System.ArgumentException: Expected module syntax body to contain property 'name'
   at Bicep.Core.Intermediate.ExpressionBuilder.GetModuleNameSyntax(ModuleSymbol moduleSymbol) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1285
   at Bicep.Core.Intermediate.ExpressionBuilder.TryGetReplacementContext(ModuleSymbol module, SyntaxBase indexExpression, SyntaxBase newContext) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1239
   at Bicep.Core.Intermediate.ExpressionBuilder.ToDependencyExpression(ResourceDependency dependency, SyntaxBase newContext) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1340
   at Bicep.Core.Intermediate.ExpressionBuilder.<>c__DisplayClass30_0.<ConvertResource>b__4(ResourceDependency x) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 731
   at System.Linq.Enumerable.SelectIPartitionIterator`2.LazyToArray()
   at System.Linq.Enumerable.SelectIPartitionIterator`2.ToArray()
   at System.Collections.Immutable.ImmutableArray.CreateRange[T](IEnumerable`1 items)
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertResource(ResourceDeclarationSyntax syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 728
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertWithoutLowering(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 214
   at Bicep.Core.Intermediate.ExpressionBuilder.<ConvertProgram>b__26_8(DeclaredResourceMetadata x) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 480
   at System.Linq.Enumerable.SelectArrayIterator`2.MoveNext()
   at System.Linq.Enumerable.OfTypeIterator[TResult](IEnumerable source)+MoveNext()
   at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at System.Collections.Immutable.ImmutableArray.CreateRange[T](IEnumerable`1 items)
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertProgram(ProgramSyntax syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 479
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertWithoutLowering(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 237
   at Bicep.Core.Intermediate.ExpressionBuilder.Convert(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 62
   at Bicep.Core.Emit.TemplateWriter.GenerateTemplateWithoutHash(PositionTrackingJsonTextWriter jsonWriter) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateWriter.cs:line 99
   at Bicep.Core.Emit.TemplateWriter.Write(SourceAwareJsonTextWriter writer) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateWriter.cs:line 79
   at Bicep.Core.Emit.TemplateEmitter.<>c__DisplayClass8_0.<Emit>b__0() in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 117
   at Bicep.Core.Emit.TemplateEmitter.EmitOrFail(Func`1 write) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 138
   at Bicep.Core.Emit.TemplateEmitter.Emit(TextWriter textWriter) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 103
   at Bicep.Core.Emit.TemplateEmitter.Emit(Stream stream) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 96
   at Bicep.LanguageServer.Handlers.BicepBuildCommandHandler.GenerateCompiledFileAndReturnBuildOutputMessageAsync(String bicepFilePath, DocumentUri documentUri) in C:\__w\1\s\bicep\src\Bicep.LangServer\Handlers\BicepBuildCommandHandler.cs:line 71
   at Bicep.LanguageServer.Handlers.BicepBuildCommandHandler.Handle(String bicepFilePath, CancellationToken cancellationToken) in C:\__w\1\s\bicep\src\Bicep.LangServer\Handlers\BicepBuildCommandHandler.cs:line 42
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.SemanticTokensDeltaPipeline`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.ResolveCommandPipeline`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestPreProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestPostProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionActionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionActionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.<RouteRequest>g__InnerRoute|7_0(IServiceScopeFactory serviceScopeFactory, Request request, TDescriptor descriptor, Object params, CancellationToken token, ILogger logger)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.RouteRequest(IRequestDescriptor`1 descriptors, Request request, CancellationToken token)
   at OmniSharp.Extensions.JsonRpc.DefaultRequestInvoker.<>c__DisplayClass10_0.<<RouteRequest>b__5>d.MoveNext()
[Error - 4:22:56 PM] Bicep build failed
Internal Error - System.ArgumentException: Expected module syntax body to contain property 'name'
   at Bicep.Core.Intermediate.ExpressionBuilder.GetModuleNameSyntax(ModuleSymbol moduleSymbol) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1285
   at Bicep.Core.Intermediate.ExpressionBuilder.TryGetReplacementContext(ModuleSymbol module, SyntaxBase indexExpression, SyntaxBase newContext) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1239
   at Bicep.Core.Intermediate.ExpressionBuilder.ToDependencyExpression(ResourceDependency dependency, SyntaxBase newContext) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1340
   at Bicep.Core.Intermediate.ExpressionBuilder.<>c__DisplayClass30_0.<ConvertResource>b__4(ResourceDependency x) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 731
   at System.Linq.Enumerable.SelectIPartitionIterator`2.LazyToArray()
   at System.Linq.Enumerable.SelectIPartitionIterator`2.ToArray()
   at System.Collections.Immutable.ImmutableArray.CreateRange[T](IEnumerable`1 items)
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertResource(ResourceDeclarationSyntax syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 728
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertWithoutLowering(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 214
   at Bicep.Core.Intermediate.ExpressionBuilder.<ConvertProgram>b__26_8(DeclaredResourceMetadata x) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 480
   at System.Linq.Enumerable.SelectArrayIterator`2.MoveNext()
   at System.Linq.Enumerable.OfTypeIterator[TResult](IEnumerable source)+MoveNext()
   at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at System.Collections.Immutable.ImmutableArray.CreateRange[T](IEnumerable`1 items)
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertProgram(ProgramSyntax syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 479
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertWithoutLowering(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 237
   at Bicep.Core.Intermediate.ExpressionBuilder.Convert(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 62
   at Bicep.Core.Emit.TemplateWriter.GenerateTemplateWithoutHash(PositionTrackingJsonTextWriter jsonWriter) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateWriter.cs:line 99
   at Bicep.Core.Emit.TemplateWriter.Write(SourceAwareJsonTextWriter writer) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateWriter.cs:line 79
   at Bicep.Core.Emit.TemplateEmitter.<>c__DisplayClass8_0.<Emit>b__0() in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 117
   at Bicep.Core.Emit.TemplateEmitter.EmitOrFail(Func`1 write) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 138
   at Bicep.Core.Emit.TemplateEmitter.Emit(TextWriter textWriter) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 103
   at Bicep.Core.Emit.TemplateEmitter.Emit(Stream stream) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 96
   at Bicep.LanguageServer.Handlers.BicepBuildCommandHandler.GenerateCompiledFileAndReturnBuildOutputMessageAsync(String bicepFilePath, DocumentUri documentUri) in C:\__w\1\s\bicep\src\Bicep.LangServer\Handlers\BicepBuildCommandHandler.cs:line 71
   at Bicep.LanguageServer.Handlers.BicepBuildCommandHandler.Handle(String bicepFilePath, CancellationToken cancellationToken) in C:\__w\1\s\bicep\src\Bicep.LangServer\Handlers\BicepBuildCommandHandler.cs:line 42
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.SemanticTokensDeltaPipeline`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.ResolveCommandPipeline`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestPreProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestPostProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionActionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionActionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.<RouteRequest>g__InnerRoute|7_0(IServiceScopeFactory serviceScopeFactory, Request request, TDescriptor descriptor, Object params, CancellationToken token, ILogger logger)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.RouteRequest(IRequestDescriptor`1 descriptors, Request request, CancellationToken token)
   at OmniSharp.Extensions.JsonRpc.DefaultRequestInvoker.<>c__DisplayClass10_0.<<RouteRequest>b__5>d.MoveNext()
[Error - 4:28:32 PM] Bicep build failed
Internal Error - System.ArgumentException: Expected module syntax body to contain property 'name'
   at Bicep.Core.Intermediate.ExpressionBuilder.GetModuleNameSyntax(ModuleSymbol moduleSymbol) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1285
   at Bicep.Core.Intermediate.ExpressionBuilder.TryGetReplacementContext(ModuleSymbol module, SyntaxBase indexExpression, SyntaxBase newContext) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1239
   at Bicep.Core.Intermediate.ExpressionBuilder.ToDependencyExpression(ResourceDependency dependency, SyntaxBase newContext) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 1340
   at Bicep.Core.Intermediate.ExpressionBuilder.<>c__DisplayClass30_0.<ConvertResource>b__4(ResourceDependency x) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 731
   at System.Linq.Enumerable.SelectIPartitionIterator`2.LazyToArray()
   at System.Linq.Enumerable.SelectIPartitionIterator`2.ToArray()
   at System.Collections.Immutable.ImmutableArray.CreateRange[T](IEnumerable`1 items)
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertResource(ResourceDeclarationSyntax syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 728
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertWithoutLowering(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 214
   at Bicep.Core.Intermediate.ExpressionBuilder.<ConvertProgram>b__26_8(DeclaredResourceMetadata x) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 480
   at System.Linq.Enumerable.SelectArrayIterator`2.MoveNext()
   at System.Linq.Enumerable.OfTypeIterator[TResult](IEnumerable source)+MoveNext()
   at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at System.Collections.Immutable.ImmutableArray.CreateRange[T](IEnumerable`1 items)
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertProgram(ProgramSyntax syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 479
   at Bicep.Core.Intermediate.ExpressionBuilder.ConvertWithoutLowering(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 237
   at Bicep.Core.Intermediate.ExpressionBuilder.Convert(SyntaxBase syntax) in C:\__w\1\s\bicep\src\Bicep.Core\Intermediate\ExpressionBuilder.cs:line 62
   at Bicep.Core.Emit.TemplateWriter.GenerateTemplateWithoutHash(PositionTrackingJsonTextWriter jsonWriter) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateWriter.cs:line 99
   at Bicep.Core.Emit.TemplateWriter.Write(SourceAwareJsonTextWriter writer) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateWriter.cs:line 79
   at Bicep.Core.Emit.TemplateEmitter.<>c__DisplayClass8_0.<Emit>b__0() in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 117
   at Bicep.Core.Emit.TemplateEmitter.EmitOrFail(Func`1 write) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 138
   at Bicep.Core.Emit.TemplateEmitter.Emit(TextWriter textWriter) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 103
   at Bicep.Core.Emit.TemplateEmitter.Emit(Stream stream) in C:\__w\1\s\bicep\src\Bicep.Core\Emit\TemplateEmitter.cs:line 96
   at Bicep.LanguageServer.Handlers.BicepBuildCommandHandler.GenerateCompiledFileAndReturnBuildOutputMessageAsync(String bicepFilePath, DocumentUri documentUri) in C:\__w\1\s\bicep\src\Bicep.LangServer\Handlers\BicepBuildCommandHandler.cs:line 71
   at Bicep.LanguageServer.Handlers.BicepBuildCommandHandler.Handle(String bicepFilePath, CancellationToken cancellationToken) in C:\__w\1\s\bicep\src\Bicep.LangServer\Handlers\BicepBuildCommandHandler.cs:line 42
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.SemanticTokensDeltaPipeline`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.ResolveCommandPipeline`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestPreProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestPostProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionActionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at MediatR.Pipeline.RequestExceptionActionProcessorBehavior`2.Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate`1 next)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.<RouteRequest>g__InnerRoute|7_0(IServiceScopeFactory serviceScopeFactory, Request request, TDescriptor descriptor, Object params, CancellationToken token, ILogger logger)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.RouteRequest(IRequestDescriptor`1 descriptors, Request request, CancellationToken token)
   at OmniSharp.Extensions.JsonRpc.DefaultRequestInvoker.<>c__DisplayClass10_0.<<RouteRequest>b__5>d.MoveNext()

To Reproduce
Copy paste the modules, right click Build ARM template
Additional context
The bicep template builds fine when I uncomment the module name.