To enable logging :

  1. Navigate to admin screen, click on Logging and profiling section
  2. In the Class/Package name field type com.mxgraph, select ALL from the New Level combobox and click Add Entry

This setting will last until the server is restarted and must be re-applied after the restart.

To provide a browser console output: 

  1. Press F12 in your browser in the tab where is opened, then click on the Console.
  2. Right click on the console output, select Copy and paste the contents into a new file and save it.