fix(error): catch socket auth error as 4xx (#4059)

* fix(error): catch socket auth error as 4xx

* Switch to type guard

---------

Co-authored-by: Theodore Li <theo@sim.ai>

Author: TheodoreSpeaks

apps/sim/app/api/auth/socket-token/route.ts

@@ -23,6 +23,18 @@ export async function POST() {
 
     return NextResponse.json({ token: response.token })
   } catch (error) {
+    // better-auth's sessionMiddleware throws APIError("UNAUTHORIZED") with no message
+    // when the session is missing/expired — surface this as a 401, not a 500.
+    if (
+      error instanceof Error &&
+      ('statusCode' in error || 'status' in error) &&
+      ((error as Record<string, unknown>).statusCode === 401 ||
+        (error as Record<string, unknown>).status === 'UNAUTHORIZED')
+    ) {
+      logger.warn('Socket token request with invalid/expired session')
+      return NextResponse.json({ error: 'Authentication required' }, { status: 401 })
+    }
+
     logger.error('Failed to generate socket token', {
       error: error instanceof Error ? error.message : String(error),
       stack: error instanceof Error ? error.stack : undefined,