server: catch internal exceptions and report something

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
server: delete the Unix domain socket if it exists already

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
read_field takes tbl fld rf, not tbl rf fld (!)

Signed-off-by: David Scott <dave.scott@eu.citrix.com>