Fix #128938: Crash duplicating paricle system in particle edit mode

In lieu of fixing the root cause, this commit requires the object to be
in object mode to duplicate particle systems, which works around the
issue because the problem is with particle edit data. This is a pragmatic
choice to focus development efforts on replacing the particle system.

source/blender/editors/physics/particle_object.cc

@@ -1334,6 +1334,10 @@ static bool duplicate_particle_systems_poll(bContext *C)
   if (BLI_listbase_is_empty(&ob->particlesystem)) {
     return false;
   }
+  if (ob->mode != OB_MODE_OBJECT) {
+    CTX_wm_operator_poll_msg_set(C, "Object must be in object mode");
+    return false;
+  }
   return true;
 }