fix: guard .first() queries against None to prevent AttributeError

Three queries called .first().value or .first().commit without
checking for None. On a fresh install or empty database, these
crash with AttributeError.

Fixed in mod_ci/controllers.py, mod_home/controllers.py, and
mod_sample/controllers.py.

Author: Dhanush Varma

mod_ci/controllers.py

@@ -993,8 +993,13 @@ def start_test(compute, app, db, repository: Repository.Repository, test, bot_to
 
     categories = Category.query.order_by(Category.id.desc()).all()
     commit_name = 'fetch_commit_' + test.platform.value
-    commit_hash = GeneralData.query.filter(GeneralData.key == commit_name).first().value
-    last_commit = Test.query.filter(and_(Test.commit == commit_hash, Test.platform == test.platform)).first()
+    commit_entry = GeneralData.query.filter(GeneralData.key == commit_name).first()
+    if commit_entry is None:
+        log.warning(f'No commit hash found for {commit_name}, skipping comparison')
+        commit_hash = None
+    else:
+        commit_hash = commit_entry.value
+    last_commit = Test.query.filter(and_(Test.commit == commit_hash, Test.platform == test.platform)).first() if commit_hash else None
 
     if last_commit is not None:
         log.debug(f"[{gcp_instance_name}] We will compare against the results of test {last_commit.id}")

mod_home/controllers.py

@@ -22,7 +22,8 @@ def before_app_request() -> None:
 @template_renderer()
 def index():
     """Render index home page."""
-    last_commit = GeneralData.query.filter(GeneralData.key == 'last_commit').first().value
+    last_commit_entry = GeneralData.query.filter(GeneralData.key == 'last_commit').first()
+    last_commit = last_commit_entry.value if last_commit_entry is not None else None
     last_release = CCExtractorVersion.query.order_by(CCExtractorVersion.released.desc()).first()
     test_access = False
     if g.user is not None and g.user.role in [Role.tester, Role.contributor, Role.admin]:

mod_sample/controllers.py

@@ -56,11 +56,13 @@ def display_sample_info(sample) -> Dict[str, Any]:
             # in case no media info present in the sample
             media_info = None
 
-    latest_commit = GeneralData.query.filter(GeneralData.key == 'last_commit').first().value
-    last_release = CCExtractorVersion.query.order_by(CCExtractorVersion.released.desc()).first().commit
+    latest_commit_entry = GeneralData.query.filter(GeneralData.key == 'last_commit').first()
+    latest_commit = latest_commit_entry.value if latest_commit_entry is not None else None
+    last_release_entry = CCExtractorVersion.query.order_by(CCExtractorVersion.released.desc()).first()
+    last_release = last_release_entry.commit if last_release_entry is not None else None
 
-    test_commit = Test.query.filter(Test.commit == latest_commit).first()
-    test_release = Test.query.filter(Test.commit == last_release).first()
+    test_commit = Test.query.filter(Test.commit == latest_commit).first() if latest_commit else None
+    test_release = Test.query.filter(Test.commit == last_release).first() if last_release else None
     regression_tests = RegressionTest.query.filter(RegressionTest.sample_id == sample.id).all()
     status = 'Unknown'
     status_release = 'Unknown'