How to customize error message when current statement is not allowed/ambiguous in grammar?

[durianwaffle]

Hi Langium community, I am implementing validator for a DSL.
I am wondering if a statement is not complete in grammar such as statement without ; which is shown below when our grammar requires ; at the end of each statement, how to customize error message such as "Expect ; at then end of statement" in this case?

[msujew]

Hey @durianwaffle,

You can create a custom ParserErrorMessageProvider:

langium/packages/langium/src/services.ts

Line 62 in 335f9a9

readonly ParserErrorMessageProvider: IParserErrorMessageProvider