Error handling attrs.define when imported locally

[George Macon]

With pytype 2024.01.05 on Python 3.8, this input:

from attrs import define

@define
class C:
    pass

produces this output from pytype-single --output - repro.py:

Traceback (most recent call last):
  File ".../bin/pytype-single", line 8, in <module>
    sys.exit(main())
  File ".../lib/python3.8/site-packages/pytype/single.py", line 87, in main
    return _run_pytype(options)
  File ".../lib/python3.8/site-packages/pytype/single.py", line 98, in _run_pytype
    return io.process_one_file(options)
  File ".../lib/python3.8/site-packages/pytype/io.py", line 77, in wrapper
    return f(*args, **kwargs)
  File ".../lib/python3.8/site-packages/pytype/io.py", line 226, in process_one_file
    ret = check_or_generate_pyi(options, loader)
  File ".../lib/python3.8/site-packages/pytype/io.py", line 77, in wrapper
    return f(*args, **kwargs)
  File ".../lib/python3.8/site-packages/pytype/io.py", line 169, in check_or_generate_pyi
    errorlog, result, ast = generate_pyi(
  File ".../lib/python3.8/site-packages/pytype/io.py", line 123, in generate_pyi
    ret = _call(analyze.infer_types, src, options, loader, ctx=ctx)
  File ".../lib/python3.8/site-packages/pytype/io.py", line 77, in wrapper
    return f(*args, **kwargs)
  File ".../lib/python3.8/site-packages/pytype/io.py", line 88, in _call
    return analyze_types(
  File ".../lib/python3.8/site-packages/pytype/analyze.py", line 121, in infer_types
    ast = ctx.vm.compute_types(defs)
  File ".../lib/python3.8/site-packages/pytype/tracer_vm.py", line 758, in compute_types
    self.pytd_for_types(defs),
  File ".../lib/python3.8/site-packages/pytype/tracer_vm.py", line 641, in pytd_for_types
    d = option.to_pytd_def(self.ctx.exitpoint, name)
  File ".../lib/python3.8/site-packages/pytype/abstract/_base.py", line 234, in to_pytd_def
    return self.ctx.pytd_convert.value_to_pytd_def(node, self, name)
  File ".../lib/python3.8/site-packages/pytype/output.py", line 461, in value_to_pytd_def
    md = metadata.to_pytd(v.to_metadata())
  File ".../lib/python3.8/site-packages/pytype/overlays/attr_overlay.py", line 231, in to_metadata
    "init": self._current_args["init"],
TypeError: 'NoneType' object is not subscriptable
File: repro.py

Changing the input to

import attrs

@attrs.define
class C:
    pass

works:

import attr
import attrs

@attr.s
class C:
    def __init__(self) -> None: ...