Run build before publish (#2409)

Author: brianc

package.json

@@ -14,6 +14,7 @@
     "build": "tsc --build",
     "build:watch": "tsc --build --watch",
     "pretest": "yarn build",
+    "prepublish": "yarn build",
     "lint": "eslint '*/**/*.{js,ts,tsx}'"
   },
   "devDependencies": {