Result.from_call: remove type ambiguity for exception/result locals

Author: RonnyPfannschmidt

src/pluggy/_result.py

@@ -57,12 +57,12 @@ def exception(self) -> BaseException | None:
     def from_call(cls, func: Callable[[], ResultType]) -> Result[ResultType]:
         """:meta private:"""
         __tracebackhide__ = True
-        result = exception = None
         try:
             result = func()
         except BaseException as exc:
-            exception = exc
-        return cls(result, exception)
+            return cls(None, exc)
+        else:
+            return cls(result, None)
 
     def force_result(self, result: ResultType) -> None:
         """Force the result(s) to ``result``.