raise exception when issue import fails for retry
diff --git a/migration/src/import_github_issues.py b/migration/src/import_github_issues.py
index 80a6507..2d04f94 100644
--- a/migration/src/import_github_issues.py
+++ b/migration/src/import_github_issues.py
@@ -47,7 +47,7 @@
         else:
             logger.error(f"Import GitHub issue {data_file} was failed. status={status}, errors={errors}")
         
-        return None
+        raise RuntimeError("Importing issue failed")
 
 
 if __name__ == "__main__":