Implementation of FormBuilder give "Cannot read properties of null"

[Ludovic1974]

I have a problem with the implementation of FormBuilder.
I have adapted the form builder as indicated in the GIT section described at https://github.com/formio/angular/wiki/Form-Builder and I am getting the following error:

core.mjs:7739 ERROR TypeError: Cannot read properties of null (reading '0')
at new Formio (Formio.js:144:19)
at FormBuilder.setForm (Form.js:185:22)
at new Form (Form.js:99:13)
at FormBuilder._createSuperInternal (FormBuilder.js:35:283)
at new FormBuilder (FormBuilder.js:50:19)
at BuilderComponent.ngOnInit (builder.component.ts:23:18)
at callHook (core.mjs:2551:22)
at callHooks (core.mjs:2520:17)
at executeInitAndCheckHooks (core.mjs:2471:9)
at refreshView (core.mjs:9595:21)

Has anyone else experienced this? How could it be resolved?

[MiguiTE]

Happens to me too