remove uneeded *Link casting

chain.go

@@ -34,7 +34,7 @@ func (c Chain) Error() string {
 	lines := make([]string, 0, len(c))
 	// source=<source> <prefix>: <error> tag=value tag2=value2 types=type1,type2
 	for i := len(c) - 1; i >= 0; i-- {
-		line := c[i].Error()
+		line := c[i].formatError()
 		lines = append(lines, line)
 	}
 	return strings.Join(lines, "\n")
@@ -60,17 +60,15 @@ type Link struct {
 	Source string
 }
 
-// Error prints a single Links error
-func (l *Link) Error() string {
+// formatError prints a single Links error
+func (l *Link) formatError() string {
 	line := fmt.Sprintf("source=%s ", l.Source)
 
 	if l.Prefix != "" {
 		line += l.Prefix + ": "
 	}
 
-	if _, isLink := l.Err.(*Link); !isLink {
-		line += l.Err.Error()
-	}
+	line += l.Err.Error()
 
 	for _, tag := range l.Tags {
 		line += fmt.Sprintf(" %s=%v", tag.Key, tag.Value)

errors.go

@@ -46,8 +46,6 @@ func Cause(err error) error {
 	switch t := err.(type) {
 	case Chain:
 		return t[0].Err
-	case *Link:
-		return t.Err
 	default:
 		return err
 	}
@@ -66,12 +64,6 @@ func HasType(err error, typ string) bool {
 				}
 			}
 		}
-	case *Link:
-		for i := 0; i < len(t.Types); i++ {
-			if t.Types[i] == typ {
-				return true
-			}
-		}
 	}
 	return false
 }
@@ -87,12 +79,6 @@ func LookupTag(err error, key string) interface{} {
 				}
 			}
 		}
-	case *Link:
-		for i := 0; i < len(t.Tags); i++ {
-			if t.Tags[i].Key == key {
-				return t.Tags[i].Value
-			}
-		}
 	}
 	return nil
 }