Remove cache file if backup returns an error

[tvb]

I noticed danpu will place files of 0 bytes (i.e.: Rah_Danpu_CpCOO0) in the temporary folder if the backup fails for any reason (like unable to connect). Those should be removed to keep the working directory clean.

[tvb]

Hmm, seems https://github.com/gocom/danpu/blob/master/src/Rah/Danpu/Base.php#L223 is not called in case of a failure?

[gocom]

The clean up is called on shutdown process via destructor method. The only case when it won't be called should be when the process dies on a FATAL error (e.g. when one doesn't capture exceptions, or the process terminates unexpectedly before normal shutdown) or other member in the shutdown chain kills the process.

[tvb]

Not sure why the tmp files remain then. I will see if I can reproduce the issue.

[tvb]

Or unable to connect is treated as FATAL?