bug in pure access analysis

[pcaversaccio]

Version Information

• vyper Version (output of vyper --version): 0.4.0b6+commit.20432c50
• OS: linux
• Python Version (output of python --version): 3.11.3

What's your issue about?

The commit 20432c5 introduced a regression. Repro example: Compile this contract and the line raises with:

Error compiling: src\snekmate\tokens\ERC721.vy
vyper.exceptions.InvalidReference: not a variable or literal: 'uint256'

  contract "src\snekmate\tokens\ERC721.vy:1306", function "_try_recover_vrs", line 1306:49
       1305     """
  ---> 1306     assert s <= convert(_MALLEABILITY_THRESHOLD, uint256), "ECDSA: invalid signature `s` value"
  -----------------------------------------------------------^
       1307

[charles-cooper]

fixed by #3906