How to customize validation error msg for unresolved variable?

[durianwaffle]

Hi Langium community, I am implementing validator for a DSL.

I am wondering how to customize validation error msg for unresolved variable?

Currently, for undeclared variables, the tooltip shows:

[msujew]

Hey @durianwaffle,

You can override the default linker for that, see:

langium/packages/langium/src/references/linker.ts

Lines 233 to 246 in 335f9a9

	protected createLinkingError(refInfo: ReferenceInfo, targetDescription?: AstNodeDescription): LinkingError {
	// Check whether the document is sufficiently processed by the DocumentBuilder. If not, this is a hint for a bug
	// in the language implementation.
	const document = findRootNode(refInfo.container).$document;
	if (document && document.state < DocumentState.ComputedScopes) {
	console.warn(`Attempted reference resolution before document reached ComputedScopes state (${document.uri}).`);
	}
	const referenceType = this.reflection.getReferenceType(refInfo);
	return {
	...refInfo,
	message: `Could not resolve reference to ${referenceType} named '${refInfo.reference.$refText}'.`,
	targetDescription
	};
	}

[durianwaffle]

Thank you @msujew
I saw an example for that.
#1086