Bug 1059591 - Incorrectly formatted remotely hosted links causes new tab to be empty [r=adw]

Use catch handler of promises to default to empty array on exceptions.

toolkit/modules/DirectoryLinksProvider.jsm

@@ -369,7 +369,7 @@ let DirectoryLinksProvider = {
       this._enhancedLinks.clear();
 
       // all directory links have a frecency of DIRECTORY_FRECENCY
-      aCallback(rawLinks.map((link, position) => {
+      return rawLinks.map((link, position) => {
         // Stash the enhanced image for the site
         if (link.enhancedImageURI) {
           this._enhancedLinks.set(NewTabUtils.extractSite(link.url), link);
@@ -378,8 +378,11 @@ let DirectoryLinksProvider = {
         link.frecency = DIRECTORY_FRECENCY;
         link.lastVisitDate = rawLinks.length - position;
         return link;
-      }));
-    });
+      });
+    }).catch(ex => {
+      Cu.reportError(ex);
+      return [];
+    }).then(aCallback);
   },
 
   init: function DirectoryLinksProvider_init() {

toolkit/modules/tests/xpcshell/test_DirectoryLinksProvider.js

@@ -426,6 +426,21 @@ add_task(function test_DirectoryLinksProvider_getLinks_noLocaleData() {
   yield promiseCleanDirectoryLinksProvider();
 });
 
+add_task(function test_DirectoryLinksProvider_getLinks_badData() {
+  let data = {
+    "en-US": {
+      "en-US": [{url: "http://example.com", title: "US"}],
+    },
+  };
+  let dataURI = 'data:application/json,' + JSON.stringify(data);
+  yield promiseSetupDirectoryLinksProvider({linksURL: dataURI});
+
+  // Make sure we get nothing for incorrectly formatted data
+  let links = yield fetchData();
+  do_check_eq(links.length, 0);
+  yield promiseCleanDirectoryLinksProvider();
+});
+
 add_task(function test_DirectoryLinksProvider_needsDownload() {
   // test timestamping
   DirectoryLinksProvider._lastDownloadMS = 0;