Error on saving when child code entry is open in editor

[zivmaor]

Describe the bug

When Trying to save (Ctrl+S) with a child code entry open in the codeEditor, an error message is shown and you cannot save the data.win file

Reproducing steps

1. Open a GML 2.0+ game (in the image I used deltarune ch 1&2).
2. Click on a child code entry from the main tree.
3. Press Ctrl+S to save.

Setup Details

Tested on both 6.1.0 and latest commit.