We chose to 'err on the side of caution' [=to be very cautious] when planning our investments.
It's better to 'err on the side of' generosity [=to be too generous] than to be too stingy.
The court 'erred' in refusing to allow bail.
(..) Look up. I think you're looking for me. I cannot believe my eyes. Spider-Man. Just the man I wanted to see. - You...err...talked to Peter? - Yeap. I want to help you, Mr. Osborn. I really, really do. I can't give you my blood. Not right now. (..)2014 The Amazing Spider-Man 2