fix: serializing exception that didn't take an argument

An exception that was instantiated without any argument could not be
serilaized before. Now, I check if any args were supplied and set the
value to an empty string if no args were passed.

src/pydase/utils/serialization/serializer.py

@@ -158,7 +158,7 @@ class Serializer:
             "doc": None,
             "readonly": True,
             "type": "Exception",
-            "value": obj.args[0],
+            "value": obj.args[0] if len(obj.args) > 0 else "",
             "name": obj.__class__.__name__,
         }