fix gc when item is deleted in observer call

src/structs/AbstractItem.js

@@ -421,13 +421,14 @@ export class AbstractItem extends AbstractStruct {
   /**
    * @param {Transaction} transaction
    * @param {StructStore} store
+   * @param {boolean} parentGCd
    *
    * @private
    */
-  gc (transaction, store) {
+  gc (transaction, store, parentGCd) {
     this.delete(transaction)
     let r
-    if (this.parent._item !== null && this.parent._item.deleted) {
+    if (parentGCd) {
       r = new GC(this.id, this.length)
     } else {
       r = new ItemDeleted(this.id, this.left, this.origin, this.right, this.rightOrigin, this.parent, this.parentSub, this.length)

src/structs/ItemDeleted.js

@@ -85,6 +85,19 @@ export class ItemDeleted extends AbstractItem {
     }
     return false
   }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {StructStore} store
+   * @param {boolean} parentGCd
+   *
+   * @private
+   */
+  gc (transaction, store, parentGCd) {
+    if (parentGCd) {
+      super.gc(transaction, store, parentGCd)
+    }
+  }
   /**
    * @param {encoding.Encoder} encoder
    * @param {number} offset

src/structs/ItemType.js

@@ -124,13 +124,13 @@ export class ItemType extends AbstractItem {
   gcChildren (transaction, store) {
     let item = this.type._start
     while (item !== null) {
-      item.gc(transaction, store)
+      item.gc(transaction, store, true)
       item = item.right
     }
     this.type._start = null
     this.type._map.forEach(item => {
       while (item !== null) {
-        item.gc(transaction, store)
+        item.gc(transaction, store, true)
         // @ts-ignore
         item = item.left
       }
@@ -141,10 +141,11 @@ export class ItemType extends AbstractItem {
   /**
    * @param {Transaction} transaction
    * @param {StructStore} store
+   * @param {boolean} parentGCd
    */
-  gc (transaction, store) {
+  gc (transaction, store, parentGCd) {
     this.gcChildren(transaction, store)
-    super.gc(transaction, store)
+    super.gc(transaction, store, parentGCd)
   }
 }