Pacify mypy

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/check_files.py b/tests/scripts/check_files.py
index 3eb60d7..a2a9dfa 100755
--- a/tests/scripts/check_files.py
+++ b/tests/scripts/check_files.py
@@ -346,10 +346,13 @@
         return False
 
 
-THIS_FILE_BASE_NAME = \
-    os.path.basename(inspect.getframeinfo(inspect.currentframe()).filename)
-LINE_NUMBER_BEFORE_LICENSE_ISSUE_TRACKER = \
-    inspect.getframeinfo(inspect.currentframe()).lineno
+def this_location():
+    frame = inspect.currentframe()
+    assert frame is not None
+    info = inspect.getframeinfo(frame)
+    return os.path.basename(info.filename), info.lineno
+THIS_FILE_BASE_NAME, LINE_NUMBER_BEFORE_LICENSE_ISSUE_TRACKER = this_location()
+
 class LicenseIssueTracker(LineIssueTracker):
     """Check copyright statements and license indications.