Use backslashreplace error strategy

mvt/common/utils.py

@@ -30,12 +30,8 @@ class CustomJSONEncoder(json.JSONEncoder):
 
     def default(self, o):
         if isinstance(o, bytes):
-            # If it's utf-8, try and use that first
-            try:
-                return o.decode("utf-8")
-            except UnicodeError:
-                # Otherwise use a hex representation for any byte type
-                return "0x" + o.hex()
+            # Decode as utf-8, replace any invalid UTF-8 bytes with escaped hex
+            return o.decode("utf-8", errors="backslashreplace")
 
         # For all other types try to use the string representation.
         return str(o)

tests/common/test_utils.py

@@ -85,7 +85,7 @@ class TestCustomJSONEncoder:
     def test__bytes_non_utf_8(self):
         assert (
             json.dumps({"identifier": b"\xa8\xa9"}, cls=CustomJSONEncoder)
-            == '{"identifier": "0xa8a9"}'
+            == """{"identifier": "\\\\xa8\\\\xa9"}"""
         )
 
     def test__bytes_valid_utf_8(self):