TypeForm error when used in function with specific structure

```python
from typing import Any

from typing_extensions import TypeForm

class ClassX: ...

class ClassY: ...

class ClassZ:
def meth(self, arg: Any): ...

def typeform_fn(arg: TypeForm[Any]) -> ClassZ: ...

def anyfn(*args: Any) -> Any: ...

def main(unrelated: list[list[int]]):
# it works without these loops
for vs in unrelated:
for _v in vs:
if anyfn(ClassX):
return

# error: Argument of type "UnionType" cannot be assigned to parameter "arg" of type "TypeForm[Any]" in function "typeform_fn"
z = typeform_fn(ClassX | ClassY)
z.meth(ClassX())
```
In my original code, it infers the wrong type in a generic TypeForm instead of argument error.

Start by running the supplied Python reproducer and compare diagnostics with and without the nested loops. Trace the TypeForm and generic inference behavior involved in the call to typeform_fn(ClassX | ClassY). Done means the reported error or inferred type matches the intended behavior for this structure without regressing the working variant.

Written by the indexing model from the issue text.