BORM Editor: failure to save DSL Editor content

[xloggr]

An attempt to save DSL Editor content causes an error.

OS: Linux (Ubuntu 22.04)
OpenPonk: v3.0.4 (nightly build has the same issue)

To reproduce:

• Run openponk-plugins script
• Select BORM Editor menu item (I tried it with an empty model as well as sample ones)
• In the BORM window click on the Diagram drop-down and select DSL Editor
• In the DSL Editor window click Save or Save as button.

The following error is displayed:

Instance of ComposableMorph did not understand #fileSave:extensions: