diff --git a/background/background.js b/background/background.js
index 9bcd2fe2..f2b7c3a1 100644
--- a/background/background.js
+++ b/background/background.js
@@ -14,9 +14,8 @@ window.API_METHODS = Object.assign(window.API_METHODS || {}, {
   installStyle: styleManager.installStyle,
   editSave: styleManager.editSave,
 
-  getTabDomain() {
-    return getTab(this.sender.tabId)
-      .then(tab => tab.url.match(/^[\w-]+:\/\/(?:[\w:-]+@)?([^:/#]+)/)[1]);
+  getTabUrlPrefix() {
+    return this.sender.tab.url.match(/^([\w-]+:\/\/[^/#]+)/)[1];
   },
 
   getStyleFromDB: id =>
@@ -100,9 +99,7 @@ navigatorUtil.onUrlChange(({tabId, frameId}, type) => {
     return;
   }
   msg.sendTab(tabId, {method: 'urlChanged'}, {frameId})
-    .catch(err => {
-      console.warn(tabId, frameId, err);
-    });
+    .catch(msg.broadcastError);
 });
 
 if (FIREFOX) {
diff --git a/content/apply.js b/content/apply.js
index dd348256..fbb39e1f 100644
--- a/content/apply.js
+++ b/content/apply.js
@@ -171,14 +171,14 @@
     if (parentDomain) {
       return Promise.resolve();
     }
-    return API.getTabDomain()
+    return API.getTabUrlPrefix()
       .then(newDomain => {
         parentDomain = newDomain;
       });
   }
 
   function updateExposeIframes() {
-    if (!prefs.get('exposeIframes') || window !== parent || !styleElements.size) {
+    if (!prefs.get('exposeIframes') || window === parent || !styleElements.size) {
       document.documentElement.removeAttribute('stylus-iframe');
     } else {
       fetchParentDomain().then(() => {
diff --git a/js/msg.js b/js/msg.js
index afc6d66a..c0130398 100644
--- a/js/msg.js
+++ b/js/msg.js
@@ -34,6 +34,7 @@ const msg = (() => {
     broadcast,
     broadcastTab,
     broadcastExtension,
+    broadcastError,
     on,
     onTab,
     onExtension,
@@ -211,8 +212,18 @@ const msg = (() => {
       }
       Promise.resolve(result)
         .then(
-          data => ({error: false, data}),
-          err => ({error: true, data: err.message || String(err)})
+          data => ({
+            error: false,
+            data
+          }),
+          err => ({
+            error: true,
+            data: Object.assign({
+              message: err.message || String(err),
+              // FIXME: do we want to pass the entire stack?
+              stack: err.stack
+            }, err) // this allows us to pass custom properties e.g. `err.index`
+          })
         )
         .then(function doResponse(responseMessage) {
           if (message.from === 'extension' && bg === undefined) {
@@ -292,7 +303,7 @@ const msg = (() => {
 
     function unwrap() {
       if (result.error) {
-        throw new Error(result.data);
+        throw Object.assign(new Error(result.data.message), result.data);
       }
       return result.data;
     }