handle require.resolve failure

if require.resolve fails, defer to default behaviour -url.resolve(base, ref)

extensions/css-language-features/server/src/utils/documentContext.ts

@@ -19,9 +19,15 @@ function getModuleNameFromPath(path: string) {
 function resolvePathToModule(moduleName: string, relativeTo: string) {
 	// if we require.resolve('my-module') then it will follow the main property in the linked package.json
 	// but we want the root of the module so resolve to the package.json and then trim
-	return require
-		.resolve(`${moduleName}/package.json`, { paths: [relativeTo] })
-		.slice(0, -12); // remove trailing `package.json`
+	let resolved;
+	try {
+		resolved = require
+			.resolve(`${moduleName}/package.json`, { paths: [relativeTo] });
+	}
+	catch (ex) {
+		return null;
+	}
+	return resolved.slice(0, -12); // remove trailing `package.json`
 }
 
 export function getDocumentContext(documentUri: string, workspaceFolders: WorkspaceFolder[]): DocumentContext {
@@ -55,8 +61,10 @@ export function getDocumentContext(documentUri: string, workspaceFolders: Worksp
 			if (ref[0] === '~' && ref[1] !== '/') {
 				const moduleName = getModuleNameFromPath(ref.substring(1));
 				const modulePath = resolvePathToModule(moduleName, base);
-				const pathWithinModule = ref.substring(moduleName.length + 2);
-				return url.resolve(modulePath, pathWithinModule);
+				if (modulePath) {
+					const pathWithinModule = ref.substring(moduleName.length + 2);
+					return url.resolve(modulePath, pathWithinModule);
+				}
 			}
 			return url.resolve(base, ref);
 		},