Fix #114152: Blender crashes when loading files with unknown IDProperty types.

Issue was reported with a 3.6 file crashing 3.3LTS, but the underlying
problem still exists in current codebase, and could also potentially be
caused by other edge-cases.

Pull Request: https://projects.blender.org/blender/blender/pulls/114397

source/blender/blenkernel/intern/idprop.cc

@@ -1307,6 +1307,10 @@ static void IDP_DirectLinkProperty(IDProperty *prop, BlendDataReader *reader);
 static void read_ui_data(IDProperty *prop, BlendDataReader *reader)
 {
   BLO_read_data_address(reader, &prop->ui_data);
+  if (!prop->ui_data) {
+    /* Can happen when opening more recent files with unknown tyes of IDProperties. */
+    return;
+  }
   BLO_read_data_address(reader, &prop->ui_data->description);
 
   switch (IDP_ui_data_type(prop)) {