With go 1.17 a change to the build flags was implemented:
https://go.googlesource.com/proposal/+/master/design/draft-gobuild.md
The formatter now automatically adds the forward-compatible build tag
format and the linter checks for them, so we need to include them in our
code.
Because the health check uses OS specific syscalls for determining the
available space on a disk that aren't available in JS/WASM builds, we
need to make sure we don't reference that code at all. Otherwise we
can't use parts of lnd as a library in projects that are being compiled
down to a WASM binary.
With this commit we rename the existing AvailableDiskSpace function to
its correct name AvailableDiskSpaceRatio as it only returns a ratio. We
then go ahead and add a new function that returns the actual number of
free bytes available on a file system.
This also fixes some comments and always returns an error instead of
panicking.
