fix compiling issues

src/Struct/Delete.js

@@ -1,4 +1,4 @@
-import StructManager from '../Util/StructManager'
+import StructManager from '../Util/StructManager.js'
 
 export default class Delete {
   constructor () {

src/Struct/Item.js

@@ -1,4 +1,3 @@
-import StructManager from '../Util/StructManager'
 
 export default class Item {
   constructor () {

src/Struct/ItemJSON.js

@@ -1,4 +1,4 @@
-import Item from './Item'
+import Item from './Item.js'
 
 export default class ItemJSON extends Item {
   constructor () {

src/Struct/ItemString.js

@@ -1,4 +1,4 @@
-import Item from './Item'
+import Item from './Item.js'
 
 export default class ItemString extends Item {
   constructor () {

src/Struct/Type.js

@@ -1,4 +1,4 @@
-import Item from './Item'
+import Item from './Item.js'
 
 export default class Type extends Item {
   constructor () {