fix: enhance error handling in build_flow and add error handling for Flow build

src/backend/base/langflow/api/v1/chat.py

@@ -356,10 +356,23 @@ async def event_generator(queue: asyncio.Queue, client_consumed_queue: asyncio.Q
             except asyncio.CancelledError:
                 vertices_task.cancel()
                 return
+            except Exception as e:
+                if isinstance(e, HTTPException):
+                    send_event("error", {"error": str(e.detail), "statusCode": e.status_code}, queue)
+                    raise e
+                send_event("error", {"error": str(e)}, queue)
+                raise e
 
             ids, vertices_to_run, graph = vertices_task.result()
         else:
-            ids, vertices_to_run, graph = await build_graph_and_get_order()
+            try:
+                ids, vertices_to_run, graph = await build_graph_and_get_order()
+            except Exception as e:
+                if isinstance(e, HTTPException):
+                    send_event("error", {"error": str(e.detail), "statusCode": e.status_code}, queue)
+                    raise e
+                send_event("error", {"error": str(e)}, queue)
+                raise e
         send_event("vertices_sorted", {"ids": ids, "to_run": vertices_to_run}, queue)
         await client_consumed_queue.get()
 

src/frontend/src/utils/buildUtils.ts

@@ -264,6 +264,14 @@ export async function buildFlowVertices({
         useFlowStore.getState().setIsBuilding(false);
         return true;
       }
+      case "error": {
+        const errorMessage = data.error;
+        console.log(data);
+        onBuildError!("Error Running Flow", [errorMessage], []);
+        buildResults.push(false);
+        useFlowStore.getState().setIsBuilding(false);
+        return true;
+      }
       default:
         return true;
     }