Delete-Plugin Error Validation Clears Form Values

[JohnONolan]

When bulk-deleting a set of plugins, if an error is encountered - all selected values are lost.

Process:

1. Go to plugins overview screen, select several (active) plugins to delete.
2. From the bulk-action dropdown menu, select "delete", then "apply"

Expected behaviour:

Error message: "You cannot delete a plugin while it is active on the main site." - Check marks are preserved, so you simply select "deactivate" and click on "apply" again.

Actual behaviour:

Error message: "You cannot delete a plugin while it is active on the main site." - All check marks lost, and you have to start all over again - which is a pain for sites with lots of plugins.