Fix generate change diff on Struct

Since we have the filteredValue variable, we need to use the same
variable when we are trying to generate the Diffs. So I fix it by
changing the variable that need to be compared.

pkg/comparator/struct.go

@@ -46,7 +46,7 @@ func (c *StructComparator) Compare(ctx context.Context, oldVal, newVal reflect.V
 			continue
 		}
 
-		if diff := diff.GenerateChangedDiff(ctx, typeField.Name, oldField, newField); diff != nil {
+		if diff := diff.GenerateChangedDiff(ctx, typeField.Name, filteredOldValue, filteredNewValue); diff != nil {
 			diffs = append(diffs, *diff)
 		}
 	}

pkg/diff/generator.go

@@ -25,6 +25,11 @@ func GenerateRemovedDiff(ctx context.Context, obj reflect.Value) Diff {
 
 func GenerateChangedDiff(ctx context.Context, fieldName string, oldVal, newVal reflect.Value) *Diff {
 	var oldI, newI interface{}
+
+	if !oldVal.IsValid() || !newVal.IsValid() {
+		return nil
+	}
+
 	switch oldVal.Kind() {
 	case reflect.Array, reflect.Slice:
 		oldI = reflectArrayToString(ctx, oldVal)