Fix a missing import and some mypy errors

quantum-viz/quantum_viz/widget.py

@@ -3,6 +3,7 @@
 """quantum-viz Viewer is a Jupyter Widget that displays the quantum-viz.js circuit
 visualizer.
 """  # noqa: D400, D205
+import json
 import uuid
 from enum import Enum
 from typing import Any
@@ -81,8 +82,12 @@ def __init__(
             self.name = "_"
 
         if not isinstance(circuit, dict):
-            from .qiskit_parser import qiskit2dict
+            from .qiskit_parser import qiskit2dict, QuantumCircuit
 
+            if not isinstance(circuit, QuantumCircuit):
+                raise TypeError(
+                    f"Received a circuit of an unsupported type: {type(circuit)}"
+                )
             circuit = qiskit2dict(circuit)
 
         self.width = width
@@ -129,7 +134,7 @@ def html_str(self, uid: Optional[str] = None) -> str:
     def _ipython_display_(self) -> None:
         """Display the widget with IPython."""
         viewer = HTML(self.html_str())
-        display(viewer)
+        display((viewer,))
 
     def browser_display(self) -> None:
         """Display the widget in the browser."""