[Bug Report] Python scaffolding fails with ModuleNotFoundError: No module named 'm2r'

Troubleshooting:

Did you try autorest --reset and attempt again? Yes

Setup (please complete the following information): **

OS: Windows
OS Version: 21H2
Mode: VSCode
VSCode extension version:
Language to be generated: ? Python
Autorest Core version: (see table)

Type	Extension Name	Version
extension	@autorest/azure-functions-python	0.1.0-preview
core	@autorest/core	3.0.6320
core	@autorest/core	3.8.3
extension	@autorest/modelerfour	4.15.414

Describe the bug

When attempting to scaffold a project using the VSCode extension (Create new project > select folder > Python > HTTP trigger(s) from OpenAPI V2/V3 Specification (Preview)), the process fails with the following error:

10:32:13 AM: Running command: "autorest --input-file:"c:\development\test\example_OpenAPIv3.json" --version:3.0.6320 --azure-functions-python --no-namespace-folders:True --no-async --generate-metadata:false --output-folder:"c:\development\test""... AutoRest code generation utility [cli version: 3.6.1; node: v17.8.0] (C) 2018 Microsoft Corporation. https://aka.ms/autorest info | AutoRest core version selected from configuration: 3.0.6320. Loading AutoRest core 'C:\Users\%USER%.autorest\@autorestcore@3.0.6320\nodemodules\@autorest\core\dist' (3.0.6320) Loading AutoRest extension '@autorest/azure-functions-python' (latest->0.1.0-preview) Loading AutoRest extension '@autorest/modelerfour' (4.15.414->4.15.414) WARNING (PreCheck/CheckDuplicateSchemas): Checking for duplicate schemas, this could take a (long) while. Run with --verbose for more detail. API Exception: {'type': 'ModuleNotFoundError', 'args': ("No module named 'm2r'",), 'message': "No module named 'm2r'"} Traceback (most recent call last): File "C:\Users\%USER%.autorest\@autorest_azure-functions-python@0.1.0-preview\node_modules\@autorest\azure-functions-python\venv\lib\site-packages\jsonrpc\manager.py", line 113, in _get_responses result = method(*request.args, **request.kwargs) File "C:\Users\%USER%.autorest\@autorest_azure-functions-python@0.1.0-preview\node_modules\@autorest\azure-functions-python\autorest\jsonrpc\server.py", line 34, in Process from ..m2r import M2R as PluginToLoad File "C:\Users\%USER%.autorest\@autorest_azure-functions-python@0.1.0-preview\node_modules\@autorest\azure-functions-python\autorest\m2r__init__.py", line 11, in import m2r ModuleNotFoundError: No module named 'm2r' Error: Server error 10:32:17 AM: Error: Failed to run "autorest" command. Check output window for more details.

Strongly suspect this is due to one of the dependencies--or rather, dependencies' dependency mistune--having a breaking change when it went from 0.8.4 to 2.0.x. The Common Errors section of the autorest.az FAQ was invaluable in figuring out the workaround (see Additional Context below for the workaround).

To Reproduce

Prerequisites:

VSCode with the Azure Functions extension
autorest installed (npm install -g autorest)
folder opened in VSCode, with an empty file named test.json

From the VSCode extension, Create new project > select folder > Python > HTTP trigger(s) from OpenAPI V2/V3 Specification (Preview)
Select test.json as the file

Error will be reproduced as described above.

Additional context Was able to resolve the issue by activating the autorest venv and installing a pinned version of mistune, then also installing the other dependencies it blocked.

C:\Users\%USER%\.autorest\@autorest_azure-functions-python@0.1.0-preview\node_modules\@autorest\azure-functions-python\venv\Scripts\activate
pip install mistune==0.8.4
pip install m2r
pip install jinja2

Once those steps are taken, it works fine. Perhaps pinning the mistune version within autorest would resolve for future users?

Azure / autorest.azure-functions