Added an warning on status code 409

index.js

@@ -51,7 +51,10 @@ async function getAndPostPullRequests() {
       headers,
       body: JSON.stringify(postData),
     });
-
+    if (postResponse.status === 409) {
+      core.warning("PR between the branches already exists.");
+      return;
+    }
     if (!postResponse.ok) {
       throw new Error(
         `HTTP error! status on creating a new PR: ${postResponse.status}`,