fix(draft): saves silently resolve if draft can't be found

spec-inbox/tasks/save-draft-spec.coffee

@@ -67,6 +67,12 @@ describe "SaveDraftTask", ->
           newBody = DatabaseStore.persistModel.calls[0].args[0].body
           expect(newBody).toBe "test body"
 
+    it "does nothing if no draft can be found in the db", ->
+      task = new SaveDraftTask("missingDraftId")
+      waitsForPromise =>
+        task.performLocal().then ->
+          expect(DatabaseStore.persistModel).not.toHaveBeenCalled()
+
   describe "performRemote", ->
     beforeEach ->
       spyOn(atom.inbox, 'makeRequest').andCallFake (opts) ->

src/flux/tasks/save-draft.coffee

@@ -35,8 +35,9 @@ class SaveDraftTask extends Task
 
     DatabaseStore.findByLocalId(Message, @draftLocalId).then (draft) =>
       if not draft?
-        errMsg = "Cannot persist changes to non-existent draft #{@draftLocalId}"
-        reject(new Error(errMsg))
+        # This can happen if a save draft task is queued after it has been
+        # destroyed. Nothing we can really do about it, so ignore this.
+        resolve()
       else if _.size(@changes) is 0
         resolve()
       else