GO-5175 Fix nil interface issue

app/ocache/ocache.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"github.com/anyproto/any-sync/util/reflection"
 	"sync"
 	"time"
 
@@ -168,7 +169,7 @@ func (c *oCache) load(ctx context.Context, id string, e *entry) {
 
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	if value == nil && err == nil {
+	if reflection.IsNilish(value) && err == nil {
 		err = fmt.Errorf("loaded value is nil, id: %s", id)
 	}
 	if err != nil {

app/ocache/ocache_test.go

@@ -67,6 +67,7 @@ func TestOCache_Get(t *testing.T) {
 		assert.Equal(t, 1, c.Len())
 		assert.NoError(t, c.Close())
 	})
+
 	t.Run("error", func(t *testing.T) {
 		tErr := errors.New("err")
 		c := New(func(ctx context.Context, id string) (value Object, err error) {
@@ -283,6 +284,17 @@ func TestOCache_GC(t *testing.T) {
 }
 
 func Test_OCache_Remove(t *testing.T) {
+	t.Run("remove puzzler", func(t *testing.T) {
+		c := New(func(ctx context.Context, id string) (value Object, err error) {
+			var p *testObject
+			return p, err
+		})
+		val, err := c.Get(context.TODO(), "test")
+		require.Error(t, err, "loaded value is nil, id: test")
+		require.Nil(t, val)
+		require.Equal(t, 0, c.Len())
+		require.NoError(t, c.Close())
+	})
 	t.Run("remove simple", func(t *testing.T) {
 		closeCh := make(chan struct{})
 		getCh := make(chan struct{})

util/reflection/reflect.go

@@ -0,0 +1,19 @@
+package reflection
+
+import "reflect"
+
+func IsNilish(val any) bool {
+	if val == nil {
+		return true
+	}
+
+	v := reflect.ValueOf(val)
+	k := v.Kind()
+	switch k {
+	case reflect.Chan, reflect.Func, reflect.Map, reflect.Pointer,
+		reflect.UnsafePointer, reflect.Interface, reflect.Slice:
+		return v.IsNil()
+	}
+
+	return false
+}