At the moment we have only TextMate-based grammar in public, which is used in VSCode and on GitHub. I see no way of conversions from TextMate to Rouge. So, the only way would be to implement it from scratch. Not so easy, but still possible. 

I can do it, I have some experience in such tasks, but don't have so much spare time at the moment. Would be interested in investing in the project?

AWS offers EC2, and it will be just virtual machines. And it will be possible to migrate any of your instances quite easy, if you would choose the same environment. If you have windows on your server, you can have Windows there as well. It's the easiest way. You would need to install the same version of the InterSystems platform you use, and repeat the configuration, copy necessary information and that's it. But for sure, could be some other options.

But AWS also suppose support for containers, this could be more difficult. And the best would be if you would use IRIS. I can help with this migration if you wish.

Yes, when you created a new class, it is just a file on your local disk. When you saved it, VSCode caught this action, and sent it to the server, and compiled it. But deleting this file, not a reason to do the same on the server.

You can delete class with Explorer view, there you may find any classes, that are stored on the server. By context menu you can Delete the item on the server, or Export it to get the local version. Icons close to class names, the same as in File Explorer view, may indicate the connection to your local file.

I think this may help

ClassMethod CleanNull(json As %DynamicObject) As %DynamicObject
{
  Set iter = json.%GetIterator()
  Set toRemove = ""
  While iter.%GetNext(.key, .value) {
    Set type = json.%GetTypeOf(key)
    If (type="null") {
      Set toRemove = toRemove _ $Listbuild(key)
    }
    ElseIf (type="object")||(type="array") {
      Set $Property(json, key) = ..CleanNull(value)
    }
  }
  Set ptr = 0, corr = 0
  While $Listnext(toRemove, ptr, key) {
    Do json.%Remove(key - corr)
    set corr = corr + 1
  }
  Return json
}

And Testing metho

ClassMethod TestJSON()
{
  set json = {
    "recipients": [ 
      { "name":"Utsavi", "email":"utsavi@gmail.com"},
      { "name":"Utsavi 1", "email":"utsavi1@gmail.com"},
      null, null
    ],
    "content":[null, {"title":"Test.pdf", "data":"ygwehfbnwfbhew"} ]
  }
  Set result = ..CleanNull(json)
  Do result.%ToJSON()
}

Will return this

{"recipients":[{"name":"Utsavi","email":"utsavi@gmail.com"},{"name":"Utsavi 1","email":"utsavi1@gmail.com"}],"content":[{"title":"Test.pdf","data":"ygwehfbnwfbhew"}]}

For performance reasons, it's possible to define an Index in a way, that some of the columns will be as part of the index itself, just for search, and some data could be in the data part of that index, which will be used to display in the result if requested. So, if your index is somehow corrupted, the SQL engine will expect the values there, and will look for it, so, it will not go to the place where the data originally seat. And as a result, you may not see some of the data in the output rows.

Sure, it’s possible to do so. React application is just a frontend side, and IRIS itself can be as a backend server. Or you can write backend server on some other language, e.g. NodeJS, Python, Java or .Net. Which will connect to IRIS as a database.

you can look at my Realworld project, in particular  realization of backend server. The project itself offers, the wide variety of frontends and backends on different languages, and with using different databases. So, you find React frontend which will work with backend on IRIS.

and look at my article about this project