fix error handling, was recursively printing errors

Author: Dean Karn

chain.go

@@ -32,7 +32,7 @@ type Chain []*Link
 // Error returns the formatted error string
 func (c Chain) Error() string {
 	lines := make([]string, 0, len(c))
-	// source=<source> <prefix>: <error> tag=value tag2=value2 types=type1,type2
+	//source=<source> <prefix>: <error> tag=value tag2=value2 types=type1,type2
 	for i := len(c) - 1; i >= 0; i-- {
 		line := c[i].formatError()
 		lines = append(lines, line)
@@ -65,10 +65,15 @@ func (l *Link) formatError() string {
 	line := fmt.Sprintf("source=%s ", l.Source)
 
 	if l.Prefix != "" {
-		line += l.Prefix + ": "
+		line += l.Prefix
 	}
 
-	line += l.Err.Error()
+	if _, ok := l.Err.(Chain); !ok {
+		if l.Prefix != "" {
+			line += ": "
+		}
+		line += l.Err.Error()
+	}
 
 	for _, tag := range l.Tags {
 		line += fmt.Sprintf(" %s=%v", tag.Key, tag.Value)