Thrown when attempting to modify a form after it has already been shown to a player. Form properties cannot be changed while the form is active.
Private
Readonly
The identifier of the form that was illegally modified after being shown.
early-execution-readable - This property can be read in early-execution mode.
Optional
Thrown when attempting to modify a form after it has already been shown to a player. Form properties cannot be changed while the form is active.