Do not log xml error responses

Author: varmar05

server/mergin/app.py

@@ -389,13 +389,16 @@ def handle_exception(e):
     def log_bad_request(response):
         """Log bad requests for easier debugging"""
         if response.status_code == 400:
-            json_body = response.get_json(silent=True)
-            if json_body and json_body.get("detail"):
-                # default response from connexion (check against swagger.yaml)
-                logging.warning(f'HTTP 400: {json_body["detail"]}')
+            if "xml" in response.content_type:
+                pass  # QGIS proxy errors are already logged at the source
             else:
-                # either WTF form validation error or custom validation with abort(400)
-                logging.warning(f"HTTP 400: {response.data}")
+                json_body = response.get_json(silent=True)
+                if json_body and json_body.get("detail"):
+                    # default response from connexion (check against swagger.yaml)
+                    logging.warning(f'HTTP 400: {json_body["detail"]}')
+                else:
+                    # either WTF form validation error or custom validation with abort(400)
+                    logging.warning(f"HTTP 400: {response.data}")
         elif response.status_code == 409:
             # request which would result in conflict, e.g. creating the same project again
             logging.warning(f"HTTP 409: {response.data}")