Fix (unreported) error in 'make_local' code of the PartialWriteContext.

Found while investigating solution for #128519.

Also added comment about usage of the `MAKE_LOCAL` option itself.

source/blender/blenkernel/BKE_blendfile.hh

@@ -236,6 +236,11 @@ class PartialWriteContext : NonCopyable, NonMovable {
      *
      * \warning By default, when #ADD_DEPENDENCIES is defined, this will also apply to all
      * dependencies as well.
+     *
+     * \note Often required when only a small subset of the ID dependencies are also added to the
+     * context (i.e. many of the added data's ID pointers are set to `nullptr`). Otherwise, some
+     * areas not expecting nullptr (like LibOverride data) may assert or error on load of the
+     * partial written blendfile.
      */
     MAKE_LOCAL = 1 << 0,
     /**

source/blender/blenkernel/intern/blendfile.cc

@@ -1779,7 +1779,7 @@ void PartialWriteContext::make_local(ID *ctx_id, const int make_local_flags)
   /* Making an ID local typically resets its session UID, here we want to keep the same value. */
   const uint ctx_id_session_uid = ctx_id->session_uid;
   BKE_main_idmap_remove_id(this->bmain.id_map, ctx_id);
-  BKE_main_idmap_insert_id(matching_uid_map_, ctx_id);
+  BKE_main_idmap_remove_id(matching_uid_map_, ctx_id);
 
   BKE_lib_id_make_local(&this->bmain, ctx_id, make_local_flags);