After migrating Front End Server to version 3 (Fiori 2.0 - SAPUI5 version 1.44), when I deploy an app using Web IDE to the ABAP system, I get the following error.

The error also appears in Web IDE console right before the confirmation of the deployment. Apart from having such error, the deploy is completed and the app works fine.
This seems to be a bug in Web IDE.
As my S-user does not enable me to open a ticket for my customer, I am opening a thread here.