temporary fix to suppress an error in doc build with qiskit 0.45

Author: itoko

docs/_ext/custom_styles/option_parser.py

@@ -201,7 +201,7 @@ def _value_repr(value: Any) -> str:
         return f"{{{dict_repr}}}"
     if value.__class__.__module__ == "builtins":
         return f":obj:`{value}`"
-    if value.__class__.__module__.startswith("qiskit"):
+    if value.__class__.__module__ and value.__class__.__module__.startswith("qiskit"):
         return f"Instance of :class:`.{value.__class__.__name__}`"
     if callable(value):
         return f"Callable :func:`{value.__name__}`"