Bug with FreeText on Forward

[HervE]

Hello forum,

I wanted to add a ticket FreeText field to the Forward action.
So I did the same as I already did to the Compose (i.e. Reply) action:
I edited SysConfig Ticket -> Frontend::Agent::Ticket::ViewForward, then modified Ticket::Frontend::AgentTicketForward###TicketFreeText. For Key=1, I set Content=2 (enabled and required).

As a result...
When I forward a message, and leave the FreeText field empty ('-' value), I get a hint pop-up saying "This field is required". Which is good.
But... when I select a value from the FreeText listbox, then submit, I get an error pop-up window "One or more errors occurred!"

I checked and compared the source codes (.dtl and .pm) for Forward and Compose actions, but did not find what caused the issue.
Could you help please?

Regards,
HervE