obs-store/local-store should upgrade webextension error to real error (…

…#7207)

* obs-store/local-store should upgrade webextension error to real error

* lint fix

* local-store - allow lastError through unchanged if error-like

app/scripts/lib/local-store.js

@@ -49,7 +49,7 @@ module.exports = class ExtensionStore {
     const local = extension.storage.local
     return new Promise((resolve, reject) => {
       local.get(null, (/** @type {any} */ result) => {
-        const err = extension.runtime.lastError
+        const err = checkForError()
         if (err) {
           reject(err)
         } else {
@@ -69,7 +69,7 @@ module.exports = class ExtensionStore {
     const local = extension.storage.local
     return new Promise((resolve, reject) => {
       local.set(obj, () => {
-        const err = extension.runtime.lastError
+        const err = checkForError()
         if (err) {
           reject(err)
         } else {
@@ -88,3 +88,17 @@ module.exports = class ExtensionStore {
 function isEmpty (obj) {
   return Object.keys(obj).length === 0
 }
+
+/**
+ * Returns an Error if extension.runtime.lastError is present
+ * this is a workaround for the non-standard error object thats used
+ * @returns {Error}
+ */
+function checkForError () {
+  const lastError = extension.runtime.lastError
+  if (!lastError) return
+  // if it quacks like an Error, its an Error
+  if (lastError.stack && lastError.message) return lastError
+  // repair incomplete error object (eg chromium v77)
+  return new Error(lastError.message)
+}