Fix for None type decode.

assignment2/run_tests.py

@@ -86,8 +86,8 @@ def test_warps_and_scenes():
             print(ret.stderr)
             bt_s, rt_s = extract_times(ret.stdout, "-" if ret.returncode == 0 else "error")
         except subprocess.TimeoutExpired as e:
-            out = e.stdout.decode('utf-8')
-            err = e.stderr.decode('utf-8')
+            out = e.stdout.decode('utf-8') if e.stdout else ""
+            err = e.stderr.decode('utf-8') if e.stderr else ""
             print(out)
             print(err)
             bt_s, rt_s = extract_times(out, "timeout")