refactor(state): extract getMissingFileHandler method for clarity

Signed-off-by: yxxhero <aiopsclub@163.com>

pkg/state/state.go

@@ -3210,7 +3210,7 @@ func (st *HelmState) ExpandedHelmfiles() ([]SubHelmfileSpec, error) {
 		}
 		if len(matches) == 0 {
 			err := fmt.Errorf("no matches for path: %s", hf.Path)
-			if *st.MissingFileHandler == "Error" {
+			if *st.getMissingFileHandler() == "Error" {
 				return nil, err
 			}
 			st.logger.Warnf("no matches for path: %s", hf.Path)
@@ -3298,6 +3298,19 @@ func (st *HelmState) getReleaseMissingFileHandler(release *ReleaseSpec) *string
 	}
 }
 
+// getMissingFileHandler returns the first non-nil MissingFileHandler in the following order:
+// - st.MissingFileHandler
+// - "Error"
+func (st *HelmState) getMissingFileHandler() *string {
+	defaultMissingFileHandler := "Error"
+	switch {
+	case st.MissingFileHandler != nil:
+		return st.MissingFileHandler
+	default:
+		return &defaultMissingFileHandler
+	}
+}
+
 func (st *HelmState) generateTemporaryReleaseValuesFiles(release *ReleaseSpec, values []any) ([]string, error) {
 	generatedFiles := []string{}