fix(community): Handle UnicodeDecodeError in GmailSearch and ensure header robustness (#1226)

Author: RONAK-AI647

libs/community/langchain_google_community/gmail/search.py

@@ -89,8 +89,8 @@ def _parse_messages(self, messages: List[Dict[str, Any]]) -> List[Dict[str, Any]
 
             email_msg = email.message_from_bytes(raw_message)
 
-            subject = email_msg["Subject"]
-            sender = email_msg["From"]
+            subject = email_msg.get("Subject", "")
+            sender = email_msg.get("From", "")
 
             message_body = ""
             if email_msg.is_multipart():
@@ -99,18 +99,22 @@ def _parse_messages(self, messages: List[Dict[str, Any]]) -> List[Dict[str, Any]
                     cdispo = str(part.get("Content-Disposition"))
                     if ctype == "text/plain" and "attachment" not in cdispo:
                         try:
-                            message_body = part.get_payload(decode=True).decode("utf-8")  # type: ignore[union-attr]
+                            message_body = part.get_payload(decode=True).decode(  # type: ignore[union-attr]
+                                "utf-8", errors="replace"
+                            )
                         except UnicodeDecodeError:
                             message_body = part.get_payload(decode=True).decode(  # type: ignore[union-attr]
-                                "latin-1"
+                                "latin-1", errors="replace"
                             )
                         break
             else:
                 try:
-                    message_body = email_msg.get_payload(decode=True).decode("utf-8")  # type: ignore[union-attr]
+                    message_body = email_msg.get_payload(decode=True).decode(  # type: ignore[union-attr]
+                        "utf-8", errors="replace"
+                    )
                 except UnicodeDecodeError:
                     message_body = email_msg.get_payload(decode=True).decode(  # type: ignore[union-attr]
-                        "latin-1"
+                        "latin-1", errors="replace"
                     )
 
             body = clean_email_body(message_body)