fix security vulnerability: replace eval()

apps/slack_data/slack_mcp_reader.py

@@ -7,6 +7,7 @@ for indexing in LEANN. It supports various Slack MCP server implementations and
 flexible message processing options.
 """
 
+import ast
 import asyncio
 import json
 import logging
@@ -146,16 +147,16 @@ class SlackMCPReader:
                     match = re.search(r"'error':\s*(\{[^}]+\})", str(e))
                     if match:
                         try:
-                            error_dict = eval(match.group(1))
-                        except (ValueError, SyntaxError, NameError):
+                            error_dict = ast.literal_eval(match.group(1))
+                        except (ValueError, SyntaxError):
                             pass
                     else:
                         # Try alternative format
                         match = re.search(r"Failed to fetch messages:\s*(\{[^}]+\})", str(e))
                         if match:
                             try:
-                                error_dict = eval(match.group(1))
-                            except (ValueError, SyntaxError, NameError):
+                                error_dict = ast.literal_eval(match.group(1))
+                            except (ValueError, SyntaxError):
                                 pass
 
                 if self._is_cache_sync_error(error_dict):