Spotify is damaged or incomplete I used to have Spotify but now it says it is damaged or incomplete, and now I can't open it again. How do I fix that?
There's official manual about it:

Reinstall Spotify
Reinstalling gives the app a new lease of life; fixing many common issues you may be experiencing.
Note: Any offline playlists will need to be re-synced once reinstalled.

Click Spotify in the menu bar then Quit Spotify.
Open Finder then click Go &gt; Library in the menu bar. (You may need to hold the Alt key if Library isn’t visible).
Open Caches and delete the com.spotify.Client folder.
Click the back arrow.
Open Application Support and delete the Spotify folder.
Download and install Spotify!