fix linters

tarwriter_test.go

@@ -26,7 +26,7 @@ func TestTarWriter(t *testing.T) {
 	go func() {
 		defer tw.Close()
 		if err := tw.WriteFile(tf, ""); err != nil {
-			t.Fatal(err)
+			t.Error(err)
 		}
 	}()
 

webfile_test.go

@@ -12,7 +12,7 @@ import (
 func TestWebFile(t *testing.T) {
 	const content = "Hello world!"
 	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		fmt.Fprintf(w, content)
+		fmt.Fprint(w, content)
 	}))
 	defer s.Close()