Add some missing dependencies

[bartbroere]

Although some issues still remain while performing npm run build, adding these dependencies fixes the problem with the missing modules.

#30

[bartbroere]

This exclusion has been removed, because we need to convert the ?? operator that appears in react-leaflet. If we can find a way to exclude all node modules again, except react-leaflet, this would probably be preferable.

[nielsdejong]

Hi Bart, Thanks for the PR!
I've been going over this issue with react-leaflet today and think I found a clean solution:
https://stackoverflow.com/a/67689949

Just using a slightly older version avoids the ?? altogether and would save us from including node_modules in webpack. I'd really like to avoid this as it increases the bundle size + triples the build time (at least on my side). I have to admit I'm far from an expert on anything babel/webpack, but this seems to be the best solution to me.

Could you try if downgrading the react-leaflet library works on your side? This is what I did:

1. Update package.json to use "@react-leaflet/core": "1.0.2", "react-leaflet": "3.1.0"
2. Delete the node_modules folder.
3. (optionally, just to be sure) npm cache clean --force
4. npm install
5. npm run dev

If this works for you, could you update the PR to set the fixed package versions & add back the exclusion rule?

[bartbroere]

Thanks for your reply. I also noticed excluding node_modules was not ideal for bundle size and build time. I considered making a more complex regex yesterday, but this is definitely more pragmatic.

I'll add some commits to this PR.