feature (is_nil): support checking func for nil (#3142)

internal/util/is_nil.go

@@ -11,7 +11,7 @@ func IsNil(i any) bool {
 		return true
 	}
 	switch reflect.TypeOf(i).Kind() {
-	case reflect.Ptr, reflect.Map, reflect.Chan, reflect.Slice:
+	case reflect.Ptr, reflect.Map, reflect.Chan, reflect.Slice, reflect.Func:
 		return reflect.ValueOf(i).IsNil()
 	}
 	return false

internal/util/is_nil_test.go

@@ -19,6 +19,7 @@ func Test_IsNil(t *testing.T) {
 	var testArrayNilPtr *[1]string
 	var testChanNilPtr *chan string
 	var testSliceNilPtr *[]string
+	var testFuncNil func()
 
 	var testChanString chan string
 
@@ -35,6 +36,7 @@ func Test_IsNil(t *testing.T) {
 		{i: &testChanString, want: false},
 		{i: "string", want: false},
 		{i: []string{}, want: false},
+		{i: func() {}, want: false},
 		{i: nil, want: true},
 		{i: testErrNilPtr, want: true},
 		{i: testMapNilPtr, want: true},
@@ -42,6 +44,7 @@ func Test_IsNil(t *testing.T) {
 		{i: testChanNilPtr, want: true},
 		{i: testChanString, want: true},
 		{i: testSliceNilPtr, want: true},
+		{i: testFuncNil, want: true},
 	}
 
 	for i, tc := range tc {