Merge pull request #114 from xocasdashdash/fixed-panic-on-bad-config

Fixed panic on bad runtime flags.

main.go

@@ -230,6 +230,9 @@ func init() {
 }
 
 func dumpFSM(mapper *mapper.MetricMapper, dumpFilename string, logger log.Logger) error {
+	if mapper.FSM == nil {
+		return fmt.Errorf("no FSM available to be dumped, possibly because the mapping contains regex patterns")
+	}
 	f, err := os.Create(dumpFilename)
 	if err != nil {
 		return err