cli: Fix "END: repeat:" logging

If an error occurs during docker exec, then the error code (stored in
"error") was previously overwritten before printed by the "END: repeat:"
log. So let's fix it so that the error code is correctly preserved and
printed.

Fixes: 5990dc7 ("cli: Add timestamps to log")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>