Check that there are no pending keyframes while writing a spec.

This can happen when a body is detached without compiling or recompiling.

Also added error catching when trying to delete a body instead of detaching it.

Fixes #2327

PiperOrigin-RevId: 712526730
Change-Id: I4b48df83120fca12d475c85b3a54893841449653

src/user/user_api.cc

@@ -254,10 +254,17 @@ int mjs_activatePlugin(mjSpec* s, const char* name) {
 
 
 
-// delete object, it will call the appropriate destructor since ~mjCBase is virtual
-void mjs_delete(mjsElement* element) {
+// delete object, return 0 if success
+int mjs_delete(mjsElement* element) {
   mjCBase* object = static_cast<mjCBase*>(element);
-  object->model->DeleteElement(element);
+  try {
+    // it will call the appropriate destructor since ~mjCBase is virtual
+    object->model->DeleteElement(element);
+    return 0;
+  } catch (mjCError& e) {
+    object->model->SetError(e);
+    return -1;
+  }
 }
 
 

src/user/user_api.h

@@ -108,8 +108,8 @@ MJAPI mjsLight* mjs_addLight(mjsBody* body, const mjsDefault* def);
 // Add frame to body.
 MJAPI mjsFrame* mjs_addFrame(mjsBody* body, mjsFrame* parentframe);
 
-// Delete object corresponding to the given element.
-MJAPI void mjs_delete(mjsElement* element);
+// Delete object corresponding to the given element, return 0 on success.
+MJAPI int mjs_delete(mjsElement* element);
 
 
 //---------------------------------- Add non-tree elements -----------------------------------------

src/user/user_model.cc

@@ -530,7 +530,6 @@ mjCModel& mjCModel::operator-=(const mjCBody& subtree) {
     ResetTreeLists();
   }
 
-  PointToLocal();
   return *this;
 }
 

src/xml/xml_native_writer.cc

@@ -858,7 +858,7 @@ mjXWriter::mjXWriter(void) {
 // cast model
 void mjXWriter::SetModel(const mjSpec* _spec, const mjModel* m) {
   if (_spec) {
-    model = (mjCModel*)_spec->element;
+    model = static_cast<mjCModel*>(_spec->element);
   }
   if (m) {
     model->CopyBack(m);
@@ -2207,6 +2207,10 @@ void mjXWriter::Keyframe(XMLElement* root) {
   // create section
   XMLElement* section = InsertEnd(root, "keyframe");
 
+  if (!model->key_pending_.empty()) {
+    throw mjXError(0, "Model has pending keyframes. It must be (re)compiled before writing XML.");
+  }
+
   // write all keyframes
   for (int i=0; i<model->nkey; i++) {
     XMLElement* elem = InsertEnd(section, "key");