Fix typo in text-serializers-from-schema function

packages/core/src/helpers/getTextSerializersFromSchema.ts

@@ -0,0 +1,9 @@
+import { Schema } from 'prosemirror-model'
+import { TextSerializer } from '../types'
+
+export function getTextSerializersFromSchema(schema: Schema): Record<string, TextSerializer> {
+  return Object.fromEntries(Object
+    .entries(schema.nodes)
+    .filter(([, node]) => node.spec.toText)
+    .map(([name, node]) => [name, node.spec.toText]))
+}