### Godot version

2992ffd25523cb8b3e0ef1b873c40115b8940178

### System information

Windows 10

### Issue description

Godot crashes randomly within a few seconds after project start when moving with the mouse.

![win_err](https://github.com/godotengine/godot/assets/52464204/1da28596-d95b-40f3-b32f-12219ec02c5d)

Started after recent merge of https://github.com/godotengine/godot/pull/67791.
I can confirm that reverting the pr fixes the crashes.

### Steps to reproduce

see desc

### Minimal reproduction project

N/A
::XIMPreeditDrawCallbackStruct *call_data) {
	DisplayServerX11 *ds = reinterpret_cast<DisplayServerX11 *>(client_data);
	WindowID window_id = ds->_get_focused_window_or_popup();
	WindowData &wd = ds->windows[window_id];
	XIMText *xim_text = call_data->text;
	if (wd.ime_active) {
		if (xim_text != nullptr) {
			String changed_text;
			if (xim_text->encoding_is_wchar) {
				changed_text = String(xim_text->string.wide_char);
			} else {
				changed_text.parse_utf8(xim_text->string.multi_byte);
			}
			if (call_data->chg_length < 0) {
				ds->im_text = ds->im_text.substr(0, call_data->chg_first) + changed_text;
			} else {
				ds->im_text = ds->im_text.substr(0, call_data->chg_first) + changed_text + ds->im_text.substr(call_data->chg_length);
			}
			
			int start = 0, count = 0;
			for (int i = 0; i < xim_text->length; i++) {
				if (xim_text->feedback[i] & XIMReverse) {
					if (count == 0) {
						start = i;
						count = 1;