fix(customresourcestate): handle nil path gracefully in StateSet metrics

pkg/customresourcestate/registry_factory.go

@@ -403,6 +403,12 @@ func (c *compiledStateSet) values(v interface{}) (result []eachValue, errs []err
 	comparable := c.ValueFrom.Get(v)
 	value, ok := comparable.(string)
 	if !ok {
+		// If the path doesn't exist (nil), return empty results instead of an error.
+		// This is consistent with how Gauge handles nil values and is expected for
+		// status fields that don't exist at resource creation time.
+		if comparable == nil {
+			return []eachValue{}, nil
+		}
 		return []eachValue{}, []error{fmt.Errorf("%s: expected value for path to be string, got %T", c.path, comparable)}
 	}
 

pkg/customresourcestate/registry_factory_test.go

@@ -333,6 +333,22 @@ func Test_values(t *testing.T) {
 			newEachValue(t, 0, "phase", "bar"),
 			newEachValue(t, 1, "phase", "foo"),
 		}},
+		{name: "stateset nil path", each: &compiledStateSet{
+			compiledCommon: compiledCommon{
+				path: mustCompilePath(t, "does", "not", "exist"),
+			},
+			LabelName: "phase",
+			List:      []string{"foo", "bar"},
+		}, wantResult: []eachValue{}, wantErrors: nil},
+		{name: "stateset non-string value", each: &compiledStateSet{
+			compiledCommon: compiledCommon{
+				path: mustCompilePath(t, "spec", "replicas"),
+			},
+			LabelName: "phase",
+			List:      []string{"1", "2"},
+		}, wantResult: []eachValue{}, wantErrors: []error{
+			errors.New("[spec,replicas]: expected value for path to be string, got float64"),
+		}},
 		{name: "status_conditions", each: &compiledGauge{
 			compiledCommon: compiledCommon{
 				path: mustCompilePath(t, "status", "conditions", "[type=Ready]", "status"),