fix(language-core): avoid generating zero-length mappings for interpo…

…lation edges

Refs: vue-vine/vue-vine#149 (comment)

packages/language-core/lib/codegen/template/interpolation.ts

@@ -23,7 +23,7 @@ export function* generateInterpolation(
 		isShorthand: boolean,
 		offset: number,
 	}[] = [];
-	for (let [section, offset, onlyError] of forEachInterpolationSegment(
+	for (let [section, offset, type] of forEachInterpolationSegment(
 		options.ts,
 		options.destructuredPropNames,
 		options.templateRefNames,
@@ -48,18 +48,24 @@ export function* generateInterpolation(
 				section = section.substring(-offset);
 				offset = 0;
 			}
-			if (start !== undefined && data !== undefined) {
-				yield [
-					section,
-					'template',
-					start + offset,
-					onlyError
-						? ctx.codeFeatures.verification
-						: typeof data === 'function' ? data(start + offset) : data,
-				];
-			}
-			else {
-				yield section;
+			const shouldSkip = section.length === 0 && (type === 'startText' || type === 'endText');
+			if (!shouldSkip) {
+				if (
+					start !== undefined
+					&& data
+				) {
+					yield [
+						section,
+						'template',
+						start + offset,
+						type === 'errorMappingOnly'
+							? ctx.codeFeatures.verification
+							: typeof data === 'function' ? data(start + offset) : data,
+					];
+				}
+				else {
+					yield section;
+				}
 			}
 			yield addSuffix;
 		}
@@ -79,7 +85,7 @@ export function* forEachInterpolationSegment(
 	code: string,
 	offset: number | undefined,
 	ast: ts.SourceFile
-): Generator<[fragment: string, offset: number | undefined, errorMappingOnly?: boolean]> {
+): Generator<[fragment: string, offset: number | undefined, type?: 'errorMappingOnly' | 'startText' | 'endText']> {
 	let ctxVars: {
 		text: string,
 		isShorthand: boolean,
@@ -124,8 +130,8 @@ export function* forEachInterpolationSegment(
 			yield [code.substring(0, ctxVars[0].offset + ctxVars[0].text.length), 0];
 			yield [': ', undefined];
 		}
-		else {
-			yield [code.substring(0, ctxVars[0].offset), 0];
+		else if (ctxVars[0].offset > 0) {
+			yield [code.substring(0, ctxVars[0].offset), 0, 'startText'];
 		}
 
 		for (let i = 0; i < ctxVars.length - 1; i++) {
@@ -145,7 +151,9 @@ export function* forEachInterpolationSegment(
 
 		const lastVar = ctxVars.at(-1)!;
 		yield* generateVar(code, destructuredPropNames, templateRefNames, lastVar);
-		yield [code.substring(lastVar.offset + lastVar.text.length), lastVar.offset + lastVar.text.length];
+		if (lastVar.offset + lastVar.text.length < code.length) {
+			yield [code.substring(lastVar.offset + lastVar.text.length), lastVar.offset + lastVar.text.length, 'endText'];
+		}
 	}
 	else {
 		yield [code, 0];
@@ -166,10 +174,10 @@ function* generateVar(
 		isShorthand: boolean,
 		offset: number,
 	} = curVar
-): Generator<[fragment: string, offset: number | undefined, errorMappingOnly?: boolean]> {
+): Generator<[fragment: string, offset: number | undefined, type?: 'errorMappingOnly']> {
 	// fix https://github.com/vuejs/language-tools/issues/1205
 	// fix https://github.com/vuejs/language-tools/issues/1264
-	yield ['', nextVar.offset, true];
+	yield ['', nextVar.offset, 'errorMappingOnly'];
 
 	const isDestructuredProp = destructuredPropNames?.has(curVar.text) ?? false;
 	const isTemplateRef = templateRefNames?.has(curVar.text) ?? false;