Replace `no Go files in` with something more readable

[jirfag]

It means that dependency wasn't loaded. And it's not obvious. We need to replace go/packages's error message.

[pmalekn]

I'm still hitting this issue having an opencv dependency:

ERRO Running error: context loading failed: failed to load program with go/packages: go [list -e -json -compiled=true -test=true -export=false -deps=true -find=false -- ./...]: exit status 2: # pkg-config --cflags  -- opencv4
Package opencv4 was not found in the pkg-config search path.
Perhaps you should add the directory containing `opencv4.pc'
to the PKG_CONFIG_PATH environment variable
No package 'opencv4' found
pkg-config: exit status 1

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.