Improve exception handler in wsgi_app method

Replace bare except clause with explicit BaseException handler for
better code clarity and to avoid potential issues with sys.exc_info().

The previous code used a bare except: clause with sys.exc_info()[1]
which is discouraged in Python. This change makes the exception
handling more explicit by catching BaseException directly, which
includes KeyboardInterrupt and SystemExit that should not be
handled by the normal exception handler.

Changes:
- Replace bare except: with except BaseException as e:
- Add explanatory comment about BaseException handling
- Remove noqa: B001 comment as it's no longer needed

All existing tests pass successfully.

src/flask/app.py

@@ -1568,8 +1568,10 @@ class Flask(App):
             except Exception as e:
                 error = e
                 response = self.handle_exception(ctx, e)
-            except:  # noqa: B001
-                error = sys.exc_info()[1]
+            except BaseException as e:
+                # Catch BaseException (KeyboardInterrupt, SystemExit, etc.)
+                # that should not be handled by the exception handler
+                error = e
                 raise
             return response(environ, start_response)
         finally: