Do not include \n in Errorf output

flag.go

diff --git a/flag.go b/flag.go
index 865259b..eba5fd9 100644
--- a/flag.go
+++ b/flag.go
@@ -262,12 +262,12 @@
 func (f *FlagSet) getFlagType(name string, ftype string, convFunc func(sval string) (interface{}, error)) (interface{}, error) {
 	flag := f.Lookup(name)
 	if flag == nil {
-		err := fmt.Errorf("flag accessed but not defined: %s\n", name)
+		err := fmt.Errorf("flag accessed but not defined: %s", name)
 		return nil, err
 	}
 
 	if flag.Value.Type() != ftype {
-		err := fmt.Errorf("trying to get %s value of flag of type %s\n", ftype, flag.Value.Type())
+		err := fmt.Errorf("trying to get %s value of flag of type %s", ftype, flag.Value.Type())
 		return nil, err
 	}