JSON output: handle bytes, and disregard JSON encoding failures

Quite unexpectedly, there is a kind of report, that has content in
bytes: ExtractCommandFailedReport, as the stdout/stderr streams are
in bytes.

It has made the metadata reporting fail in one case, so the custom
JSON encoding has been changed to make sensible output when running
into an unknown object, but never fail.

Author: e3krisztian

unblob/models.py

@@ -136,18 +136,29 @@ def to_json(self, indent="  "):
 
 class _JSONEncoder(json.JSONEncoder):
     def default(self, obj):
-        if isinstance(obj, Enum):
-            return obj.name
-
         if attr.has(type(obj)):
             extend_attr_output = True
             attr_output = attr.asdict(obj, recurse=not extend_attr_output)
             attr_output["__typename__"] = obj.__class__.__name__
             return attr_output
 
+        if isinstance(obj, Enum):
+            return obj.name
+
         if isinstance(obj, Path):
             return str(obj)
-        return json.JSONEncoder.default(self, obj)
+
+        if isinstance(obj, bytes):
+            try:
+                return obj.decode()
+            except UnicodeDecodeError:
+                return str(obj)
+
+        logger.error(f"JSONEncoder met a non-JSON encodable value: {obj}")
+        # the usual fail path of custom JSONEncoders is to call the parent and let it fail
+        #     return json.JSONEncoder.default(self, obj)
+        # instead of failing, just return something usable
+        return f"Non-JSON encodable value: {obj}"
 
 
 class ExtractError(Exception):