[6.x] Only remove Bard set when backspace key is hit

[duncanmcclean]

This pull request fixes an issue where pressing any character key while a Bard set is selected would delete the set.

This was happening because TipTap/ProseMirror's default behavior for selected nodes is to replace them when typing.

This PR fixes it by adding keyboard shortcuts that intercept printable character keys (letters, numbers, punctuation) when a set node is selected, preventing accidental deletion.

Backspace and Delete keys still work normally for intentional removal.

---

Partially fixes #14185

[andjsch]

This is nice. Had that happen in v5 also from time to time.

[jasonvarga]

I don't love that we have to whitelist every character. I'm sure we've missed some.

Instead, we should just allow the ones we want.

Here's the AI suggestion. I haven't tested it:

Use a ProseMirror plugin with handleKeyDown instead of per-key shortcuts. One handler, no key enumeration, and all printable keys are covered. Example—add a third plugin in addProseMirrorPlugins():

import { NodeSelection } from '@tiptap/pm/state';

// In addProseMirrorPlugins(), add:
new Plugin({
    key: new PluginKey('setBlockCharacterInput'),
    props: {
        handleKeyDown(view, event) {
            const { state } = view;
            const { selection } = state;
            if (!(selection instanceof NodeSelection) || selection.node.type !== type) return false;
            const k = event.key;
            if (k === 'Backspace' || k === 'Delete' || k === 'Enter' || k === 'Escape' || k === 'Tab') return false;
            if (k.length === 1) return true; // block single character input
            return false;
        },
    },
}),

Then remove addKeyboardShortcuts() and keep the NodeSelection import for the selection instanceof NodeSelection check. This avoids maintaining a list of keys and closes the gap for keys like !, @, #, etc.

[jasonvarga]

☝️

[jasonvarga]

This prevents deletions when you focus the bard set directly.

You can still delete the set when you highlight around the bard set.

This is still a big improvement. As shown in the issue, the issue he runs into is that he clicks on things within the bard set and accidentally deletes the whole thing with a keystroke. That part is solved. 👍

If you select around the bard set, that is more intentional so deleting that way is fine. Maybe can be improved later somehow.