Address review comment

1. Fail if gh release is not found

Author: viveksinghggits

scripts/release/kubectl_mongodb/promote_kubectl_plugin.py

@@ -290,10 +290,15 @@ def upload_assets_to_github_release(asset_paths: list[str], release_version: str
         for r in repo.get_releases():
             if r.tag_name == release_version:
                 gh_release = r
+                break
+
+        if gh_release is None:
+            logger.error(
+                f"Could not find release (published or draft) with tag '{release_version}'. Please ensure the release exists."
+            )
+            sys.exit(2)
     except GithubException as e:
-        logger.debug(
-            f"ERROR: Could not find release with tag '{release_version}'. Please ensure release exists already. Error: {e}"
-        )
+        logger.debug(f"Failed to retrieve releases from the repository {GITHUB_REPO}. Error: {e}")
         sys.exit(2)
 
     for asset_path in asset_paths: