Fix #110096: Crash Crash on calling curve pen operator

Changed poll function to `ED_operator_editcurve` to prevent
crashing when accessed from the developer menu in modes other
than edit mode.

Pull Request: https://projects.blender.org/blender/blender/pulls/110619

source/blender/editors/curve/editcurve_pen.cc

@@ -1843,7 +1843,7 @@ void CURVE_OT_pen(wmOperatorType *ot)
   /* api callbacks */
   ot->invoke = curve_pen_invoke;
   ot->modal = curve_pen_modal;
-  ot->poll = ED_operator_view3d_active;
+  ot->poll = ED_operator_editcurve;
 
   /* flags */
   ot->flag = OPTYPE_UNDO;