Stop source map generation

This isn't doing anything for us currently, and I suspect is also the source of
this error when trying to run a binary built using `yarn build:quick`

> DevTools failed to load source map: Could not load content for next://app/preload.js.map:
  Unexpected token '<', "<!DOCTYPE "... is not valid JSON

Note that the renderer process already has source maps.

desktop/tsconfig.json

@@ -48,8 +48,6 @@
 
         /* Emit the generated JS into `app/` */
         "outDir": "app",
-        /* Generate source maps */
-        "sourceMap": true,
 
         /* Temporary overrides to get things to compile with the older config */
         "strict": false,