upgrading a plugin that doesn't exist

[jdingman]

USE CASE:

1. User is on the plugin upgrade page
   
2. User deletes said plugin that requires upgrade via FTP or SSH
   
3. User returns to the plugin upgrade page, clicks on "upgrade automatically" for said plugin

RESULT: screen prints.... "The plugin is at the latest version."

...it should probably say: "Plugin does not exist, please return to the plugin screen" or something like that.

This seems like an extreme fringe case - i.e. you'd have to 'try' to break things in order to see this happen. Either way, the only issue here is with the text of the message, not with what WordPress is actually doing.

If you've got your heart set on changing the message, though, you could prototype a routine that verifies the plug-in exists after checking the version. Right now, it looks like it's checking against the version number stored in the database (lightweight, just a quick options lookup). You could change it so that it loads the plug-in header instead and verifies the version against that information - if the header loads, the plug-in exists.

This would also prevent the (extreme fringe) case where someone:

1. Is on the plug-in upgrade page
2. Updates said plug-in via FTP or SSH
3. Returns to the upgrade page and clicks on "upgrade automatically"

The plug-in would already be up-to-date and wouldn't need an update ... the system should alert the user accordingly.

Based on it being an extreme edge case, and the final output is not "breaking" just displaying something unhelpful.