system/dbus: dump messages on early fault

In the current app implementation this gets dumped in the wait method after resuming output. Wait is never called in an early fault condition, so any error messages get lost.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/system/dbus.go

@@ -127,6 +127,10 @@ func (d *DBus) apply(_ *I) error {
 
 	// ready is not nil if the proxy process faulted
 	if err := <-ready; err != nil {
+		// dump message buffer as caller does not dump this
+		// in an early fault condition
+		d.out.Dump()
+
 		// note that err here is either an I/O error or a predetermined unexpected behaviour error
 		return fmsg.WrapErrorSuffix(err,
 			"message bus proxy fault after start:")