fix: a plain build starts with no split paths

scripts/generate_pack.py

@@ -2337,6 +2337,8 @@ def _run_platform_packs(
             else:
                 print(f"\nGenerating pack for {representative} {_pack_label(source, required_only)}...")
 
+            zip_path = None
+            zip_paths: list = []
             try:
                 tc = target_cores_cache.get(representative) if args.target else None
                 if args.split:

tests/test_system_selection.py

@@ -85,6 +85,7 @@ class ADeclinedBuildIsAFailure(unittest.TestCase):
                 capture_output=True, text=True, cwd=str(REPO_ROOT), timeout=600, check=False,
             )
             self.assertNotEqual(proc.returncode, 0, proc.stdout + proc.stderr)
+            self.assertNotIn("Traceback", proc.stderr, proc.stderr)
             self.assertEqual([p for p in os.listdir(tmp) if p.endswith(".zip")], [])