Bug: RangeSelection using root splices text from last node

[9larsons]

Lexical version: v0.11.1

Steps To Reproduce

1. Create root selection on an editor with text as the last node
2. Delete the selection

Link to code example:
https://github.com/facebook/lexical/pull/4586/files this PR is what surfaced this issue, but I'm also trying to implement a similar solution (using root-based RangeSelection) as a workaround for another bug and am running in to the issue there as well.

editor.registerCommand(
    KEY_MODIFIER_COMMAND,
    (event) => {
        const {metaKey} = event;
        if (metaKey && event.keyCode === 65) {
          const root = $getRoot();
          root.select(0, root.getChildrenSize());
          event.preventDefault();
          return true;
        }
}

This works great with a decorator node in the content, but if it's just text (or text is the last child of root), the content is spliced because of this line.

The current behavior

If a text node is the last node in root, the content is spliced based on the root offset, which doesn't make sense.

The expected behavior

If a text node is the last node in root, do not splice the content.

Note, the workaround to this is inserting a blank paragraph node on select all, but that can also be confusing/annoying for users.