add getNodeType

packages/core/src/utils/getNodeType.ts

@@ -0,0 +1,9 @@
+import { NodeType, Schema } from 'prosemirror-model'
+
+export default function getNodeType(nameOrType: string | NodeType, schema: Schema): NodeType {
+  if (typeof nameOrType === 'string') {
+    return schema.nodes[nameOrType]
+  }
+
+  return nameOrType
+}