Add back typecheck

package.json

@@ -9,6 +9,7 @@
   "scripts": {
     "start": "parcel index.html",
     "build": "parcel build index.html --no-source-maps --detailed-report",
+    "typecheck": "tsc --noEmit --jsx preserve",
     "lint": "eslint --ext .ts,.tsx,.js .",
     "lint-fix": "eslint --ext .ts,.tsx,.js . --fix"
   },
@@ -27,6 +28,7 @@
     "parcel": "2.9.3",
     "process": "^0.11.10",
     "stream-browserify": "^3.0.0",
+    "tsc": "^2.0.4",
     "typescript": "^4.4.3",
     "util": "^0.12.4"
   },

yarn.lock

@@ -3529,6 +3529,11 @@ to-regex-range@^5.0.1:
   dependencies:
     is-number "^7.0.0"
 
+tsc@^2.0.4:
+  version "2.0.4"
+  resolved "https://registry.yarnpkg.com/tsc/-/tsc-2.0.4.tgz#5f6499146abea5dca4420b451fa4f2f9345238f5"
+  integrity sha512-fzoSieZI5KKJVBYGvwbVZs/J5za84f2lSTLPYf6AGiIf43tZ3GNrI1QzTLcjtyDDP4aLxd46RTZq1nQxe7+k5Q==
+
 tslib@^1.8.1:
   version "1.14.1"
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.14.1.tgz#cf2d38bdc34a134bcaf1091c41f6619e2f672d00"