fixed issue where install script errors were not properly propagated

Summary:
Our post install scripts didn't propagate installation errors in CI (or locally), leading to problems only appearing later in time, causing a lot of lost time {emoji:1f605}

Also moved printing what package is installing to _before_ running the script, so that you have actual useful info in case it fails.

Compilation errors of pkg and doctor were printed in our CI, but never threw exceptions.

Fixed the cause of those compilation errors as well using `skipLibCheck` like done in the root tsconfig

Reviewed By: jknoxville

Differential Revision: D20470985

fbshipit-source-id: 1b13d4d2c096f253cc9c1f0aac06982fc4aedf55

desktop/pkg/tsconfig.json

@@ -8,6 +8,7 @@
     "strict": true,
     "importHelpers": true,
     "esModuleInterop": true,
+    "skipLibCheck": true,
     "allowJs": true
   },
   "include": [