Marks cannot be untoggled in table cell selection if head cell is empty

[anna-holmes]

Description
After selecting some cells in a table, any mark you attempt to toggle (with toggleBold, toggleItalic, etc) will not toggle off correctly IF the last selected cell does not have any content.

By "last selected cell" I mean the head cell -- this issue happens whether or not the last selected cell is above the first selected cell in the table.

Steps to reproduce the bug
Steps to reproduce the behavior:

1. Go to https://codesandbox.io/s/tiptap-issue-template-forked-3xzhz?file=/src/components/Tiptap.vue
2. Click "insert table"
3. Type some words in the left-top and left-center cells
4. Highlight all 3 cells in the left column
5. Click "toggle bold" twice
6. Notice that the content was bolded correctly but not unbolded on the second click

Expected behavior
If you create a cell selection in which all cells with content have a particular mark applied, toggling that mark should cause it to be removed in each of those cells.

Screenshot, video, or GIF
https://user-images.githubusercontent.com/46762176/134964945-ad4d61a6-a6e4-420d-9ef7-26ca735a927e.mp4
https://user-images.githubusercontent.com/46762176/134965224-78d6e4d5-9ba4-4a7d-8344-c4fc4f21bd5a.mp4
https://user-images.githubusercontent.com/46762176/134965502-cf7ef9c8-b53a-402d-b211-1bf15c98d765.mp4

Environment?

• operating system: Big Sur
• browser: Chrome
• mobile/desktop: Desktop
• tiptap version: 2.0.0-beta.105

Additional context
I'm thinking this might be a Tiptap issue and not a ProseMirror issue, because this issue doesn't occur in this basic ProseMirror table sandbox https://codesandbox.io/s/3gmyc?file=/src/index.js

[hanspagel]

3 hours for a bug fix, not bad @philippkuehn ✨

[anna-holmes]

Amazing! Just pulled this down and it's working perfectly (of course)