LPE message fields are empty

Summary:

LPEs using MessageParam don't show any message...

Steps to reproduce:

• open Inkscape
• draw a shape
• add Power stroke effect

What happened?

Empty message in the LPE panel:

What should have happened?

Message "Ctrl + click on existing node and move it" should be there

Version info

Inkscape 1.4-dev (9236c9f756, 2024-03-03, custom)

Probably introduced in !5980 (merged)