[runsc] Print file name when cannot load state file

[copybara-service]

[runsc] Print file name when cannot load state file

When runsc does not work, there are messages like

loading container: file does not exist
...
loading sandbox: file does not exist

The problem here is, there is no indication of file path, making it harder to debug.

I don't have access to environment where these errors appear, so I cannot repro. Better diagnostics would help.

There's a comment in code suggesting that error code is important, so we cannot modify error IIUC

gvisor/runsc/container/state_file.go

Line 81 in 9c490f8

// Preserve error so that callers can distinguish 'not found' errors.

so my suggestion is to log the file name.

FUTURE_COPYBARA_INTEGRATE_REVIEW=#11457 from stepancheg:state-file f0ac6d5