Variables section only shows 'Invalid variable attributes'.

[bartgenuit]

Environment data

• debugpy version: 1.4.1 (run import debugpy; print(debugpy.__version__) if uncertain)
• OS and version: Windows 10, 2004, build 19041.1165
• Python version (& distribution if applicable, e.g. Anaconda): 3.7.11
• Using VS Code or Visual Studio: VS Code (version 1.59.0)

Actual behavior

Variables section shows no variables, show error message 'Invalid variable attributes' instead. This seems to be with particular Python version (3.7) in combination with particular Flask submodules (session and request).

Expected behavior

Variables shown in the variable section of VS Code.

Steps to reproduce:

1. Install Remote-Container extension (ms-vscode-remote.remote-containers, tested with v0.191.1).
2. Clone the 'Try Python remote container' repository:
   git clone https://github.com/microsoft/vscode-remote-try-python.git
3. Set the Python version VARIANT: "3.7" in .devcontainer/devcontainer.json.
4. Build and run container (e.g. VSCode > F1 > Remote-Containers: Open Folder in container, then select the repository we just downloaded)
5. Modify app.py to trigger the behavior:

from flask import Flask
from flask import session
from flask import request
app = Flask(__name__)
breakpoint()

@app.route("/")
def hello():
    return app.send_static_file("index.html")

6. Start debugging with F5.

[int19h]

This also reproduces locally. The relevant bit from debugpy logs:

D+00002.047: Server[1] --> {
                 "pydevd_cmd_id": 502,
                 "seq": 52,
                 "type": "response",
                 "request_seq": 17,
                 "success": true,
                 "command": "variables",
                 "body": {
                     "variables": [
                         {
                             "name": "<error>",
                             "value": "Traceback (most recent call last):\n  File \"c:\\Users\\pminaev\\.vscode\\extensions\\ms-python.python-2021.8.1105858891\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_comm.py\", line 776, in internal_get_variable_json\n    variables.append(child_var.get_var_data(fmt=fmt))\n  File \"c:\\Users\\pminaev\\.vscode\\extensions\\ms-python.python-2021.8.1105858891\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_suspended_frames.py\", line 51, in get_var_data\n    self.value, to_string=safe_repr)\n  File \"c:\\Users\\pminaev\\.vscode\\extensions\\ms-python.python-2021.8.1105858891\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_xml.py\", line 298, in get_variable_details\n    _type, type_name, resolver = get_type(v)\n  File \"c:\\Users\\pminaev\\.vscode\\extensions\\ms-python.python-2021.8.1105858891\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_xml.py\", line 151, in get_type\n    return self._get_type(o, type_object, type_name)\n  File \"c:\\Users\\pminaev\\.vscode\\extensions\\ms-python.python-2021.8.1105858891\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_xml.py\", line 154, in _get_type\n    resolver = self._type_to_resolver_cache.get(type_object)\nTypeError: unhashable type: 'LocalProxy'\n",
                             "type": "<error>"
                         }
                     ]
                 }
             }

The LocalProxy type mentioned appears to be werkzeug.local.LocalProxy; both session and request have this type.

[int19h]

The underlying problem is that this:

hash(session.__class__)

fails, because session.__class__ is not actually a type object in this case. It appears to be this Werkzeug issue:

pallets/werkzeug#2188

That said, we should be able to gracefully handle stuff like this, since any type can redefine __class__ in a similar way. The easiest would probably be to check if the returned value is a type, and whether the object queried is actually an instance of that type; if not, fall back to type().