sq gets borked if the active source in sq.yml get corrupted

[neilotoole]

In the sq config file, there is a sources/active field. If this gets corrupted (e.g. the file is manually edited to remove that source), then sq displays an error. However, it should be possible for sq to zero out the sources/active field on that first error, so that the command will work next time.

[neilotoole]

Fixed.