[PATCH 2/2] perf treport: Fix profile builder type narrowing in progress callback

[James Clark]

Mypy does not retain the narrowing of an optional local variable inside
the nested progress callback, causing the perf build to fail with:

  python/treport.py:649: error: Item "None" of "ProfileBuilder | None" has no attribute "cancelled" [union-attr]

Check the loading builder before assigning it to profile so the captured
variable is inferred as ProfileBuilder rather than
Optional[ProfileBuilder]. Keep the existing assertion and background
loading behavior.

Fixes: b379b70b7b7b ("perf treport: Show the profile while it loads")
Assisted-by: Codex:GPT-6.1-Sol
Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
---
 tools/perf/python/treport.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/python/treport.py b/tools/perf/python/treport.py
index e02121475370..fb583786b17a 100755
--- a/tools/perf/python/treport.py
+++ b/tools/perf/python/treport.py
@@ -638,8 +638,9 @@ class ReportApp(App):
     @work(thread=True, exclusive=True)
     def load_profile(self) -> None:
         """Build the profile in a thread so the UI stays responsive."""
-        profile = self.loading
-        assert profile is not None
+        loading = self.loading
+        assert loading is not None
+        profile = loading
 
         def progress() -> None:
             try:

-- 
2.43.0