Improve Deps error reporting for Cordova

In Chrome, the built-in, non-standard property `e.stack` starts with `“Error: ”+e.message`.  So we said `(e.stack || e.message)`.  However, in Cordova, e.stack does not include e.message.  So detect whether e.stack includes e.message or not and act accordingly (to avoid losing the message or printing it twice).

Also add some comments and stop printing “Exception from Deps afterFlush function function”.