fix: error swallowing when using continue (#4354)
### Description
Fixes regression added in #4254 where we swallowed exit codes when
`--continue` was used to invoke turbo.
Don't love this fix, but it was the most straightforward fix I could
see. @mehulkar unsure if I'm handling the case where an execution
summary doesn't have an exit code correctly.
### Testing Instructions
See added integration test and the changed run summary test which now
has a 1 exit code.
