Addin gets fooled by deleted data
If I have a spreadsheet which I check, and then say the right hand column was just some notes that are not really important, and may have special characters in - i decide its best to just delete that column. If I select it and press the delete key the entries disappear. When I then check the data again it reports blank cells and non-contiguous data. If I highlight the column where that notes data was, and then right click and choose delete to delete the entire column (rather than press del key and just blank the cells), then the errors go away when check again.
Might want to let people know when completely deleting a column to use the later method, not just the del key.