fix some bugs

packages/core/src/Editor.ts

@@ -20,6 +20,7 @@ import { Mark } from './Mark'
 import { Extensions, UnionToIntersection } from './types'
 import * as extensions from './extensions'
 import style from './style'
+import { AllExtensions } from '.'
 
 export { extensions }
 
@@ -40,8 +41,6 @@ export interface CommandsSpec {
   [key: string]: CommandSpec
 }
 
-export interface AllExtensions {}
-
 export type UnfilteredCommands = {
   [Item in keyof AllExtensions]: AllExtensions[Item] extends Extension<any, infer ExtensionCommands>
     ? ExtensionCommands
@@ -70,6 +69,8 @@ export type ChainedCommands = {
   run: () => boolean
 }
 
+export type CanCommands = SingleCommands & { chain: () => ChainedCommands }
+
 type EditorContent = string | JSON | null
 
 interface HTMLElement {