Before v1, the blinking module would not throw when the passed led file
does not exist. This change checks for file existence and defaults to
`/dev/null` otherwise
Change-type: patch
This updates balena lint to the latest version to enable eslint support
and unblock Typescript updates. This is a huge number of changes as the
linting rules are much more strict now, requiring modifiying most files
in the codebase. This commit also bumps the test dependency `rewire` as
that was interfering with the update of balena-lint
Change-type: patch
