assertions in remove physical

panda/src/physics/physicsManager.cxx

@@ -106,6 +106,7 @@ remove_angular_force(AngularForce *f) {
 ////////////////////////////////////////////////////////////////////
 void PhysicsManager::
 remove_physical(Physical *p) {
+  nassertv(this);
   nassertv(p);
   pvector< Physical * >::iterator found;
 
@@ -113,8 +114,11 @@ remove_physical(Physical *p) {
   if (found == _physicals.end()) {
     return;
   }
+  nassertv(*found == p);
+  nassertv(p->_physics_manager != (PhysicsManager *) NULL);
   p->_physics_manager = (PhysicsManager *) NULL;
   _physicals.erase(found);
+  nassertv(_physicals.end() == find(_physicals.begin(), _physicals.end(), p));
 }
 
 ////////////////////////////////////////////////////////////////////