Crash: `AttributeError` since concat f-string and string as a class function return value

[plucury]

Bug description

When parsing the following a.py:

class A():
    def a(self):
        desc = f"" + 'a'
        return desc

Command used

pylint a.py

Pylint output

pylint crashed with a ``AstroidError`` and with the following stacktrace:

Traceback (most recent call last):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/lint/pylinter.py", line 788, in _lint_file
    check_astroid_module(module)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/lint/pylinter.py", line 1020, in check_astroid_module
    retval = self._check_astroid_module(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/lint/pylinter.py", line 1072, in _check_astroid_module
    walker.walk(node)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/utils/ast_walker.py", line 90, in walk
    self.walk(child)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/utils/ast_walker.py", line 90, in walk
    self.walk(child)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/utils/ast_walker.py", line 87, in walk
    callback(astroid)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/checkers/classes/special_methods_checker.py", line 183, in visit_functiondef
    inferred = _safe_infer_call_result(node, node)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/checkers/classes/special_methods_checker.py", line 42, in _safe_infer_call_result
    value = next(inferit)
            ^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/scoped_nodes/scoped_nodes.py", line 1658, in infer_call_result
    yield from returnnode.value.infer(context)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/node_ng.py", line 168, in infer
    for i, result in enumerate(self._infer(context=context, **kwargs)):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/decorators.py", line 86, in inner
    yield next(generator)
          ^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/decorators.py", line 49, in wrapped
    for res in _func(node, context, **kwargs):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/bases.py", line 177, in _infer_stmts
    for inf in stmt.infer(context=context):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/node_ng.py", line 168, in infer
    for i, result in enumerate(self._infer(context=context, **kwargs)):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/decorators.py", line 86, in inner
    yield next(generator)
          ^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/decorators.py", line 49, in wrapped
    for res in _func(node, context, **kwargs):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/bases.py", line 177, in _infer_stmts
    for inf in stmt.infer(context=context):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/node_ng.py", line 168, in infer
    for i, result in enumerate(self._infer(context=context, **kwargs)):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/decorators.py", line 69, in inner
    yield next(generator)
          ^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/decorators.py", line 49, in wrapped
    for res in _func(node, context, **kwargs):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/_base_nodes.py", line 336, in _filter_operation_errors
    for result in infer_callable(context):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/node_classes.py", line 1555, in _infer_binop
    yield from self._infer_binary_operation(
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/nodes/_base_nodes.py", line 641, in _infer_binary_operation
    left_type = helpers.object_type(left)
                ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/helpers.py", line 106, in object_type
    types = set(_object_type(node, context))
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/astroid/helpers.py", line 68, in _object_type
    for inferred in node.infer(context=context):
                    ^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'infer'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/lint/pylinter.py", line 752, in _lint_files
    self._lint_file(fileitem, module, check_astroid_module)
  File "/Users/xuzhangxuan/.pyenv/versions/3.11.10/envs/pylint_debug/lib/python3.11/site-packages/pylint/lint/pylinter.py", line 790, in _lint_file
    raise astroid.AstroidError from e
astroid.exceptions.AstroidError

Expected behavior

No crash.

Pylint version

pylint 3.3.5
astroid 3.3.9
Python 3.11.10 (main, Mar 11 2025, 10:34:09) [Clang 16.0.0 (clang-1600.0.26.6)]

OS / Environment

darwin (Darwin)

[plucury]

It seems like this will be fixed in version 4.0.0 with this commit：805a3f6