Failed to install update in Safari

[RSully]

I have 0.8.7.0 installed and Safari tried to auto update to 0.8.8.2. During this update, and subsequent manual attempts to update, I just get an error

Safari can’t install this extension
An error occurred while installing the extension “µBlock”.

[chrisaljoudi]

Please uninstall µBlock, quit Safari, launch, and then install the latest µBlock. This is a bug outside µBlock's control, unfortunately.

[RSully]

Having this problem again now. This is the only extension I have experienced this with.