Test that the help's examples read no data and list the exit codes, a data path that is no directory says so in one shape, a choice suggests a record of one, a JSON syntax error names its line and column, and FakeStruct says no data is loaded

loading_test.go

@@ -205,7 +205,7 @@ func TestNewErrors(t *testing.T) {
 	if err := os.WriteFile(file, []byte("{}"), 0o644); err != nil {
 		t.Fatal(err)
 	}
-	if _, err := New(WithDataPath(file)); err == nil || !strings.Contains(err.Error(), "xx_XX is not a directory") {
+	if _, err := New(WithDataPath(file)); err == nil || !strings.Contains(err.Error(), "xx_XX: not a directory") {
 		t.Errorf("New(file) = %v, want not-a-directory error", err)
 	}
 	// Invalid JSON in a category file fails.