You could try to implement the log module form the appstore, this will allow you to log errors to your mendix database and create the notification mechnisme on top of that.
Or have a look at the java code behind that module and build your own logsubscriber that notifies directly.
See: https://marketplace.mendix.com/link/component/159/CAPE-Groep-B.V./Logging-Module
One approach we use is to use the Logging module. This logs each entry into an entity in the Logging module. We query these entities in a scheduled event and if it matches specific criteria we send an alert via email.
https://marketplace.mendix.com/link/component/159
I hope this helps.