return error for duplicate keys rather than panicking

api/internal/wrappy/factory_test.go

@@ -306,13 +306,16 @@ items:
 			assert.False(t, tc.exp.isErr)
 			assert.Equal(t, len(tc.exp.out), len(rs))
 			for i := range rs {
+				rsMap, err := rs[i].Map()
+				assert.NoError(t, err)
 				assert.Equal(
-					t, fmt.Sprintf("%v", tc.exp.out[i]), fmt.Sprintf("%v", rs[i].Map()))
+					t, fmt.Sprintf("%v", tc.exp.out[i]), fmt.Sprintf("%v", rsMap))
 				if n != "listWithAnchors" {
 					// https://github.com/kubernetes-sigs/kustomize/issues/3271
-					if !reflect.DeepEqual(tc.exp.out[i], rs[i].Map()) {
+					m, _ := rs[i].Map()
+					if !reflect.DeepEqual(tc.exp.out[i], m) {
 						t.Fatalf("%s:\nexpected: %v\n  actual: %v",
-							n, tc.exp.out[i], rs[i].Map())
+							n, tc.exp.out[i], m)
 					}
 				}
 			}

api/internal/wrappy/wnode.go

@@ -220,7 +220,7 @@ func (wn *WNode) GetString(path string) (string, error) {
 }
 
 // Map implements ifc.Kunstructured.
-func (wn *WNode) Map() map[string]interface{} {
+func (wn *WNode) Map() (map[string]interface{}, error) {
 	return wn.node.Map()
 }
 

api/internal/wrappy/wnode_test.go

@@ -559,7 +559,9 @@ func TestGetSlice(t *testing.T) {
 }
 
 func TestMapEmpty(t *testing.T) {
-	assert.Equal(t, 0, len(NewWNode().Map()))
+	newNodeMap, err := NewWNode().Map()
+	assert.NoError(t, err)
+	assert.Equal(t, 0, len(newNodeMap))
 }
 
 func TestMap(t *testing.T) {
@@ -577,7 +579,8 @@ func TestMap(t *testing.T) {
 		},
 	}
 
-	actual := wn.Map()
+	actual, err := wn.Map()
+	assert.NoError(t, err)
 	if diff := cmp.Diff(expected, actual); diff != "" {
 		t.Fatalf("actual map does not deep equal expected map:\n%v", diff)
 	}