style: narrow the log pop-out view for the pyright gate

The Optional _popout_view is assert-narrowed once after opening; the
unguarded accesses were the last three diff-gate violations.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/unit/gui/test_log_panel.py

@@ -13,11 +13,13 @@ def test_log_popout_mirrors_and_clears(qtbot):
     dock._open_popout()
     assert dock._popout is not None
     assert dock._popout.isVisible()
+    popout_view = dock._popout_view
+    assert popout_view is not None
     # History copied on open, live lines reach both views.
-    assert "first line" in dock._popout_view.toPlainText()
+    assert "first line" in popout_view.toPlainText()
     dock.emitter.message.emit("second line")
     assert "second line" in dock.view.toPlainText()
-    assert "second line" in dock._popout_view.toPlainText()
+    assert "second line" in popout_view.toPlainText()
 
     # Reopening reuses the window instead of stacking mirrors.
     popout = dock._popout
@@ -26,4 +28,4 @@ def test_log_popout_mirrors_and_clears(qtbot):
 
     dock.clear()
     assert dock.view.toPlainText() == ""
-    assert dock._popout_view.toPlainText() == ""
+    assert popout_view.toPlainText() == ""