feat: adding error handling

Author: JakePartusch

index.js

@@ -19,8 +19,16 @@ const waitForUrl = async (url, MAX_TIMEOUT) => {
 const run = async () => {
   try {
     const PR_NUMBER = github.context.payload.number;
+    if (!PR_NUMBER) {
+      core.setFailed(
+        "Action must be run in conjunction with the `pull_request` event"
+      );
+    }
     const MAX_TIMEOUT = Number(core.getInput("site_name")) || 60;
     const siteName = core.getInput("site_name");
+    if (!siteName) {
+      core.setFailed("Required field `site_name` was not provided");
+    }
     const url = `https://deploy-preview-${PR_NUMBER}--${siteName}.netlify.com`;
     console.log(`Waiting for a 200 from: ${url}`);
     await waitForUrl(url, MAX_TIMEOUT);