Every. Single. Time there's an update for Illustrator I have to uninstall Illustrator and the Creative Cloud Desktop app, then re-install both apps, in order for the update to work. Otherwise I get the error code 145 when trying to only update the app.
This has been happening for over a year at this point.
Sorry about the delayed response and the trouble you are facing with Illustrator. Error 145 indicates that the installer is unable to overwrite some of the currently written files or folders. This could be related to permission errors. Does your user account has Admin rights?