[Bug]: AssertionError in UserDefinedType.__init__()

[webthethird]

Describe the issue:

I've got a fuzz testing contract that I generated using my differential fuzzing test generator, and it compiles, but I was getting an error when trying to test it with Echidna. So I ran slither --print echidna ./src/test/compound/DiffFuzzCustomInitialization.sol and saw the AssertionError below.

It appears to be asserting that None is either a Contract, Structure or Enum.

Code example to reproduce the issue:

https://github.com/webthethird/solidity-diff-fuzz-upgrades/blob/main/src/test/compound/DiffFuzzCustomInitialization.sol
https://github.com/webthethird/solidity-diff-fuzz-upgrades/blob/main/src/test/compound/DiffFuzzUpgrades.sol

Version:

0.9.2

Relevant log output:

Error in /home/webthethird/Ethereum/solidity-diff-fuzz-upgrades/src/test/compound/DiffFuzzCustomInitialization.sol
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/__main__.py", line 834, in main_impl
    ) = process_all(filename, args, detector_classes, printer_classes)
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/__main__.py", line 98, in process_all
    ) = process_single(compilation, args, detector_classes, printer_classes)
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/__main__.py", line 76, in process_single
    slither = Slither(target, ast_format=ast, **vars(args))
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slither.py", line 133, in __init__
    self._init_parsing_and_analyses(kwargs.get("skip_analyze", False))
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slither.py", line 153, in _init_parsing_and_analyses
    raise e
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slither.py", line 149, in _init_parsing_and_analyses
    parser.analyze_contracts()
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/solc_parsing/slither_compilation_unit_solc.py", line 529, in analyze_contracts
    self._convert_to_slithir()
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/solc_parsing/slither_compilation_unit_solc.py", line 740, in _convert_to_slithir
    func.generate_slithir_and_analyze()
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/core/declarations/function.py", line 1750, in generate_slithir_and_analyze
    node.slithir_generation()
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/core/cfg/node.py", line 719, in slithir_generation
    self._irs = convert_expression(expression, self)
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slithir/convert.py", line 119, in convert_expression
    result = apply_ir_heuristics(result, node)
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slithir/convert.py", line 1858, in apply_ir_heuristics
    irs = propagate_type_and_convert_call(irs, node)
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slithir/convert.py", line 442, in propagate_type_and_convert_call
    new_ins = propagate_types(ins, node)
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/slithir/convert.py", line 774, in propagate_types
    ir.lvalue.set_type(UserDefinedType(contract))
  File "/usr/local/lib/python3.10/dist-packages/slither_analyzer-0.9.2-py3.10.egg/slither/core/solidity_types/user_defined_type.py", line 19, in __init__
    assert isinstance(t, (Contract, Enum, Structure))
AssertionError

[0xalpharush]

This is a duplicate of #1594 and related to this PR #1539

[webthethird]

This is a duplicate of #1594 and related to this PR #1539

Ahh, didn't see that. Seems like PR #1539 is only blocked because of an old bug in the CI re pip-audit. If the CI checks were run again it'd probably pass. Anyway, either that or my fix in #1786 should probably be merged, right?