manager: rework error handling and logging in manager_reload()

manager: rework error handling and logging in manager_reload()

let's clean up error handling and logging in manager_reload() a bit.
Specifically: make sure we log about every error we might encounter at
least and at most once.

When we encounter an error before the "point of no return" then log at
LOG_ERR about it and propagate it. Otherwise, eat it up, but warn about
it and proceed, it's the best we can do.