From b6f3843e9f7b288856295c2e0ab44efd4eeea1f6 Mon Sep 17 00:00:00 2001
From: Dominik Jain <dominik.jain@outlook.com>
Date: Wed, 16 Apr 2025 10:34:30 +0200
Subject: [PATCH] Improve handling of fatal exceptions (as showing the GUI,
 even on the main thread, can fail), making sure that the error is furthermore
 logged or at least written to stderr

---
 src/serena/agent.py | 26 +++++++++++++++++++++++++-
 src/serena/agno.py  |  5 ++---
 src/serena/mcp.py   |  5 ++---
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/serena/agent.py b/src/serena/agent.py
index b755bd2f..d9a78d57 100644
--- a/src/serena/agent.py
+++ b/src/serena/agent.py
@@ -6,6 +6,7 @@ import inspect
 import json
 import os
 import platform
+import sys
 import traceback
 from abc import ABC
 from collections import defaultdict
@@ -16,6 +17,7 @@ from typing import TYPE_CHECKING, Any, Self, TypeVar, Union, cast
 
 import yaml
 from sensai.util import logging
+from sensai.util.logging import FallbackHandler
 from sensai.util.string import ToStringMixin, dict_string
 
 from multilspy import SyncLanguageServer
@@ -40,6 +42,27 @@ TTool = TypeVar("TTool", bound="Tool")
 SUCCESS_RESULT = "OK"
 
 
+def show_fatal_exception_safe(e: Exception) -> None:
+    """
+    Shows the given exception in the GUI log viewer on the main thread and ensures that the exception is logged or at
+    least printed to stderr.
+    """
+    # Make sure the error is logged (adding a fallback handler which writes to stderr in case there is no other handler)
+    fallback_handler = FallbackHandler(logging.StreamHandler(sys.stderr))
+    Logger.root.addHandler(fallback_handler)
+    log.error(f"Fatal exception: {e}", exc_info=e)
+
+    # attempt to show the error in the GUI
+    try:
+        # NOTE: The import can fail on macOS if Tk is not available (depends on Python interpreter installation, which uv
+        #   used as a base); while tkinter as such is always available, its dependencies can be unavailable on macOS.
+        from serena.gui_log_viewer import show_fatal_exception
+
+        show_fatal_exception(e)
+    except:
+        pass
+
+
 class SerenaConfigError(Exception):
     pass
 
@@ -171,7 +194,8 @@ class SerenaAgent:
             if platform.system() == "Darwin":
                 log.warning("GUI log window is not supported on macOS")
             else:
-                # even importing on macOS may fail since tkinter is not available by default
+                # even importing on macOS may fail if tkinter dependencies are unavailable (depends on Python interpreter installation
+                # which uv used as a base, unfortunately)
                 from serena.gui_log_viewer import GuiLogViewer, GuiLogViewerHandler
 
                 log_level = self.serena_config.gui_log_window_level
diff --git a/src/serena/agno.py b/src/serena/agno.py
index 2af283db..3157229e 100644
--- a/src/serena/agno.py
+++ b/src/serena/agno.py
@@ -15,8 +15,7 @@ from dotenv import load_dotenv
 from sensai.util.logging import LogTime
 
 from serena import serena_root_path
-from serena.agent import SerenaAgent, Tool
-from serena.gui_log_viewer import show_fatal_exception
+from serena.agent import SerenaAgent, Tool, show_fatal_exception_safe
 
 log = logging.getLogger(__name__)
 
@@ -92,7 +91,7 @@ class SerenaAgnoAgentProvider:
                 try:
                     serena_agent = SerenaAgent(project_file)
                 except Exception as e:
-                    show_fatal_exception(e)
+                    show_fatal_exception_safe(e)
                     raise
 
             # Even though we don't want to keep history between sessions,
diff --git a/src/serena/mcp.py b/src/serena/mcp.py
index d55a5b1c..2de742af 100644
--- a/src/serena/mcp.py
+++ b/src/serena/mcp.py
@@ -15,8 +15,7 @@ from mcp.server.fastmcp.utilities.func_metadata import func_metadata
 from sensai.util import logging
 from sensai.util.helper import mark_used
 
-from serena.agent import SerenaAgent, Tool
-from serena.gui_log_viewer import show_fatal_exception
+from serena.agent import SerenaAgent, Tool, show_fatal_exception_safe
 
 log = logging.getLogger(__name__)
 LOG_FORMAT = "%(levelname)-5s %(asctime)-15s %(name)s:%(funcName)s:%(lineno)d - %(message)s"
@@ -100,7 +99,7 @@ def create_mcp_server() -> FastMCP:
             # project_activation_callback=update_tools
         )
     except Exception as e:
-        show_fatal_exception(e)
+        show_fatal_exception_safe(e)
         raise
 
     @asynccontextmanager