Skipping of Diagnostics

[cdietrich]

we have the following usecase

• we have a lightweight compile mode that works with a single file only and thus references to the outside world will be broken
• references that we know are inside the file still should be treated as error

here is what we currently do

• override processLinkingErrors and do somthing like in the snipped below
• i wonder if this can and or should be done more generic e.g. by returning and filtering undefined from toDiagnostic (would change the signature

protected override processLinkingErrors(
    document: LangiumDocument,
    diagnostics: Diagnostic[],
    _options: ValidationOptions
  ): void {
    for (const reference of document.references) {
      const linkingError = reference.error
      if (linkingError !== undefined) {
        const info: DiagnosticInfo<AstNode, string> = {
          node: linkingError.container,
          property: linkingError.property,
          index: linkingError.index,
          data: {
            code: DocumentValidator.LinkingError,
            containerType: linkingError.container.$type,
            property: linkingError.property,
            refText: linkingError.reference.$refText,
          } satisfies LinkingErrorData,
        }
        if (!this.shouldSkip(info)) {
          diagnostics.push(this.toDiagnostic("error", linkingError.message, info))
        }
      }
    }
  }
  
  shouldSkip<N extends AstNode>(info: DiagnosticInfo<N, string>): boolean {
    if (..) {
        return true
    }
    return false
  }

[spoenemann]

Extending the signature to allow undefined sounds good to me.