Bug 1758250 - deal with non-existing url values from session restore so they don't brick other functionality, r=dao

Differential Revision: https://phabricator.services.mozilla.com/D142947

browser/base/content/tabbrowser.js

@@ -2211,11 +2211,12 @@
             break;
           case "currentURI":
             getter = () => {
-              let url = SessionStore.getLazyTabValue(aTab, "url");
               // Avoid recreating the same nsIURI object over and over again...
               if (browser._cachedCurrentURI) {
                 return browser._cachedCurrentURI;
               }
+              let url =
+                SessionStore.getLazyTabValue(aTab, "url") || "about:blank";
               return (browser._cachedCurrentURI = Services.io.newURI(url));
             };
             break;
@@ -2255,7 +2256,8 @@
             break;
           case "remoteType":
             getter = () => {
-              let url = SessionStore.getLazyTabValue(aTab, "url");
+              let url =
+                SessionStore.getLazyTabValue(aTab, "url") || "about:blank";
               // Avoid recreating the same nsIURI object over and over again...
               let uri;
               if (browser._cachedCurrentURI) {

browser/components/sessionstore/SessionStore.jsm

@@ -4341,7 +4341,7 @@ var SessionStoreInternal = {
    * @returns a flag indicates whether a connection has been made
    */
   prepareConnectionToHost(tab, url) {
-    if (!url.startsWith("about:")) {
+    if (url && !url.startsWith("about:")) {
       let principal = Services.scriptSecurityManager.createNullPrincipal({
         userContextId: tab.userContextId,
       });