this is still not working here on Thunderbird 102.0.3 (windows 64 bit version). If you have many error messages copying / exporting etc. fails.
Copy all messages / Save all Message to file - throws:
TypeError: toolbox is null2 context-menu.js:341:42
We can select some messages and use "Copy Message"
If we select all messages (with Ctrl+A) right-click removes the selection.