Handle optional components gracefully when files don't exist

Co-authored-by: JoeRobich <611219+JoeRobich@users.noreply.github.com>

Author: Copilot

src/lsptoolshost/extensions/builtInComponents.ts

@@ -44,12 +44,20 @@ export const componentInfo: { [key: string]: ComponentInfo } = {
     },
 };
 
-export function getComponentPaths(componentName: string, options: LanguageServerOptions | undefined): string[] {
+export function getComponentPaths(
+    componentName: string,
+    options: LanguageServerOptions | undefined,
+    isOptional = false
+): string[] {
     const component = componentInfo[componentName];
     const baseFolder = getComponentFolderPath(component, options);
     const paths = component.componentDllPaths.map((dllPath) => path.join(baseFolder, dllPath));
     for (const dllPath of paths) {
         if (!fs.existsSync(dllPath)) {
+            if (isOptional) {
+                // Component is optional and doesn't exist - return empty array
+                return [];
+            }
             throw new Error(`Component DLL not found: ${dllPath}`);
         }
     }

src/lsptoolshost/server/roslynLanguageServer.ts

@@ -1026,7 +1026,7 @@ export class RoslynLanguageServer {
 
         // Also include the Xaml Dev Kit extensions, if enabled.
         if (languageServerOptions.enableXamlTools) {
-            getComponentPaths('xamlTools', languageServerOptions).forEach((path) =>
+            getComponentPaths('xamlTools', languageServerOptions, true).forEach((path) =>
                 additionalExtensionPaths.push(path)
             );
         }
@@ -1096,7 +1096,7 @@ export class RoslynLanguageServer {
             await exports.setupTelemetryEnvironmentAsync(env);
         }
 
-        getComponentPaths('roslynCopilot', languageServerOptions).forEach((extPath) => {
+        getComponentPaths('roslynCopilot', languageServerOptions, true).forEach((extPath) => {
             additionalExtensionPaths.push(extPath);
         });
     }

src/razor/src/extension.ts

@@ -104,7 +104,7 @@ export async function activate(
             await setupDevKitEnvironment(dotnetInfo.env, csharpDevkitExtension, logger);
 
             if (vscode.env.isTelemetryEnabled) {
-                const razorComponentPaths = getComponentPaths('razorDevKit', undefined);
+                const razorComponentPaths = getComponentPaths('razorDevKit', undefined, true);
                 if (razorComponentPaths.length !== 1) {
                     logger.logError('Failed to find Razor DevKit telemetry extension path.', undefined);
                 } else {