Fix GitlabCommentReporter raise unhandled exception if no merge reque…

…st has been found

megalinter/reporters/GitlabCommentReporter.py

@@ -30,15 +30,19 @@ def produce_report(self):
             gitlab_repo = config.get("CI_PROJECT_NAME")
             gitlab_project_id = config.get("CI_PROJECT_ID")
             gitlab_merge_request_id = config.get("CI_MERGE_REQUEST_ID", "")
-            if (
-                gitlab_merge_request_id == ""
-                and config.get("CI_OPEN_MERGE_REQUESTS", "") != ""
-            ):
-                gitlab_merge_request_id = (
-                    config.get("CI_OPEN_MERGE_REQUESTS", "missing!missing")
-                    .split(",")[0]
-                    .split("!")[1]
-                )
+            if gitlab_merge_request_id == "":
+                if config.get("CI_OPEN_MERGE_REQUESTS", "") != "":
+                    gitlab_merge_request_id = (
+                        config.get("CI_OPEN_MERGE_REQUESTS", "missing!missing")
+                        .split(",")[0]
+                        .split("!")[1]
+                    )
+                else:
+                    logging.info(
+                        "[Gitlab Comment Reporter] No merge request has been found, so no comment has been posted"
+                    )
+                    return
+
             gitlab_server_url = config.get("CI_SERVER_URL", self.gitlab_server_url)
             action_run_url = config.get("CI_JOB_URL", "")
             p_r_msg = build_markdown_summary(self, action_run_url)