Bug 904477 - Add missing error handlers for promises used in SessionStore. r=ttaubert

browser/components/sessionstore/src/SessionStore.jsm

@@ -413,7 +413,7 @@ let SessionStoreInternal = {
 
       // Let everyone know we're done.
       this._deferredInitialized.resolve();
-    });
+    }, Cu.reportError);
   },
 
   initSession: function ssi_initSession() {

browser/components/sessionstore/src/_SessionFile.jsm

@@ -259,7 +259,7 @@ let SessionFileInternal = {
     SessionWorker.post("writeLoadStateOnceAfterStartup", [aLoadState]).then(msg => {
       this._recordTelemetry(msg.telemetry);
       return msg;
-    });
+    }, Cu.reportError);
   },
 
   createBackupCopy: function (ext) {

browser/components/sessionstore/src/nsSessionStartup.js

@@ -81,7 +81,8 @@ SessionStartup.prototype = {
     }
 
     _SessionFile.read().then(
-      this._onSessionFileRead.bind(this)
+      this._onSessionFileRead.bind(this),
+      Cu.reportError
     );
   },