fix optional chaining

babel.config.js

@@ -3,6 +3,7 @@ module.exports = {
     '@babel/preset-env',
   ],
   plugins: [
+    '@babel/plugin-proposal-nullish-coalescing-operator',
     '@babel/plugin-proposal-optional-chaining',
   ],
 }

package.json

@@ -21,6 +21,7 @@
     "reset": "yarn clean:packages && rm -rf ./**/.cache && rm -rf ./**/node_modules && rm -rf ./yarn.lock && yarn install"
   },
   "devDependencies": {
+    "@babel/plugin-proposal-nullish-coalescing-operator": "^7.10.4",
     "@babel/plugin-proposal-optional-chaining": "^7.11.0",
     "@babel/preset-env": "^7.11.5",
     "@types/prosemirror-commands": "^1.0.3",

tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "esnext",
+    "target": "es2019",
     "module": "esnext",
     "strict": true,
     "jsx": "preserve",