fix: abort connection on error preventing infinite build (#6050)

* fix: abort connection on build errors

* fix: streamline error message formatting in ErrorMessage class

* test: remove timeout from waitForSelector in generalBugs-shard-10.spec.ts

---------

Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>

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

@@ -389,7 +389,6 @@ async def build_flow(
             raise
         event_manager.on_vertices_sorted(data={"ids": ids, "to_run": vertices_to_run})
         await client_consumed_queue.get()
-
         tasks = []
         for vertex_id in ids:
             task = asyncio.create_task(build_vertices(vertex_id, graph, client_consumed_queue, event_manager))

src/backend/base/langflow/schema/message.py

@@ -368,18 +368,9 @@ class MessageResponse(DefaultModel):
 class ErrorMessage(Message):
     """A message class specifically for error messages with predefined error-specific attributes."""
 
-    def __init__(
-        self,
-        exception: BaseException,
-        session_id: str | None = None,
-        source: Source | None = None,
-        trace_name: str | None = None,
-        flow_id: UUID | str | None = None,
-    ) -> None:
-        # This is done to avoid circular imports
-        if exception.__class__.__name__ == "ExceptionWithMessageError" and exception.__cause__ is not None:
-            exception = exception.__cause__
-        # Get the error reason
+    @staticmethod
+    def _format_markdown_reason(exception: BaseException) -> str:
+        """Format the error reason with markdown formatting."""
         reason = f"**{exception.__class__.__name__}**\n"
         if hasattr(exception, "body") and isinstance(exception.body, dict) and "message" in exception.body:
             reason += f" - **{exception.body.get('message')}**\n"
@@ -391,7 +382,37 @@ class ErrorMessage(Message):
             reason += f" - **Details:**\n\n```python\n{exception!s}\n```\n"
         else:
             reason += " - **An unknown error occurred.**\n"
+        return reason
 
+    @staticmethod
+    def _format_plain_reason(exception: BaseException) -> str:
+        """Format the error reason without markdown."""
+        if hasattr(exception, "body") and isinstance(exception.body, dict) and "message" in exception.body:
+            reason = f"{exception.body.get('message')}\n"
+        elif hasattr(exception, "code"):
+            reason = f"Code: {exception.code}\n"
+        elif hasattr(exception, "args") and exception.args:
+            reason = f"{exception.args[0]}\n"
+        elif isinstance(exception, ValidationError):
+            reason = f"{exception!s}\n"
+        else:
+            reason = "An unknown error occurred.\n"
+        return reason
+
+    def __init__(
+        self,
+        exception: BaseException,
+        session_id: str | None = None,
+        source: Source | None = None,
+        trace_name: str | None = None,
+        flow_id: UUID | str | None = None,
+    ) -> None:
+        # This is done to avoid circular imports
+        if exception.__class__.__name__ == "ExceptionWithMessageError" and exception.__cause__ is not None:
+            exception = exception.__cause__
+
+        plain_reason = self._format_plain_reason(exception)
+        markdown_reason = self._format_markdown_reason(exception)
         # Get the sender ID
         if trace_name:
             match = re.search(r"\((.*?)\)", trace_name)
@@ -402,7 +423,7 @@ class ErrorMessage(Message):
             session_id=session_id,
             sender=source.display_name if source else None,
             sender_name=source.display_name if source else None,
-            text=reason,
+            text=plain_reason,
             properties=Properties(
                 text_color="red",
                 background_color="red",
@@ -422,7 +443,7 @@ class ErrorMessage(Message):
                             type="error",
                             component=source.display_name if source else None,
                             field=str(exception.field) if hasattr(exception, "field") else None,
-                            reason=reason,
+                            reason=markdown_reason,
                             solution=str(exception.solution) if hasattr(exception, "solution") else None,
                             traceback=traceback.format_exc(),
                         )