Merge branch 'master' into publicPath-output

Author: adubrouski

client-src/overlay.js

@@ -664,10 +664,16 @@ const createOverlay = (options) => {
       if (!error && !message) {
         return;
       }
+
       // if error stack indicates a React error boundary caught the error, do not show overlay.
-      if (error.stack && error.stack.includes("invokeGuardedCallbackDev")) {
+      if (
+        error &&
+        error.stack &&
+        error.stack.includes("invokeGuardedCallbackDev")
+      ) {
         return;
       }
+
       handleError(error, message);
     });
 

lib/Server.js

@@ -3108,8 +3108,6 @@ class Server {
        */
       const allHeaders = [];
 
-      allHeaders.push({ key: "X_TEST", value: "TEST" });
-
       if (!Array.isArray(headers)) {
         // eslint-disable-next-line guard-for-in
         for (const name in headers) {