feat: enhance error handling for LLM API calls

Add LLM error alert functionality to display specific error messages based on API responses. Introduce new LlmErrorAlertType interface for structured error alerts. Update chat components to manage and display LLM error alerts effectively, improving user feedback during error scenarios.

app/routes/api.chat.ts

@@ -375,16 +375,34 @@ async function chatAction({ context, request }: ActionFunctionArgs) {
   } catch (error: any) {
     logger.error(error);
 
+    const errorResponse = {
+      error: true,
+      message: error.message || 'An unexpected error occurred',
+      statusCode: error.statusCode || 500,
+      isRetryable: error.isRetryable !== false, // Default to retryable unless explicitly false
+      provider: error.provider || 'unknown',
+    };
+
     if (error.message?.includes('API key')) {
-      throw new Response('Invalid or missing API key', {
-        status: 401,
-        statusText: 'Unauthorized',
-      });
+      return new Response(
+        JSON.stringify({
+          ...errorResponse,
+          message: 'Invalid or missing API key',
+          statusCode: 401,
+          isRetryable: false,
+        }),
+        {
+          status: 401,
+          headers: { 'Content-Type': 'application/json' },
+          statusText: 'Unauthorized',
+        },
+      );
     }
 
-    throw new Response(null, {
-      status: 500,
-      statusText: 'Internal Server Error',
+    return new Response(JSON.stringify(errorResponse), {
+      status: errorResponse.statusCode,
+      headers: { 'Content-Type': 'application/json' },
+      statusText: 'Error',
     });
   }
 }