Merge branch 'pr/123'

Change-Id: Ic6ebfb2610227e24a970e50c4664a10a478d2bf3

Author: skriptble

mongo/single_result.go

@@ -33,12 +33,13 @@ type SingleResult struct {
 // will be returned. If there were no returned documents, ErrNoDocuments is
 // returned.
 func (sr *SingleResult) Decode(v interface{}) error {
+	if sr.err != nil {
+		return sr.err
+	}
 	if sr.reg == nil {
 		return bson.ErrNilRegistry
 	}
 	switch {
-	case sr.err != nil:
-		return sr.err
 	case sr.rdr != nil:
 		if v == nil {
 			return nil