How to catch DOM exception in Nim code?

[halloleo]

When targeting the JS backend I want to catch the JavaScript DOMException "A 
network error occurred.".

So I tried:
    
    
      var httpRequest = newXMLHttpRequest()
      
      try:
        httpRequest.open("GET", cstring"http://ireallydontexist.org/";, 
async=false)
        httpRequest.send()
        ...
      except Exception as ex:
        echo &"Exception!!! {repr(ex)}"
    
    
    Run

but this doesn't catch the DOM exception. I suspect Nim's `Exception` is not 
'broad' enough to catch the DOM exception.

Is there another exception in Nim which would catch this?