I have a generic error handler, when the response from the service layer in not JSON

...
else if (xhr.status)
  growl($.i18n('http_error',xhr.status))
else if (xhr.statusText)
  growl($.i18n('network_error',xhr.statusText))
...

I've got a bunch of screenshots showing, that the second if is activated, so I have XHR with an empty status, and statusText having content 'error'.

I'm interpreting such cases and a network connection error, but is my premise correct? In what circumstances browser (the screenshots are from Chrome) gives back XHR with such constellation of values? Is this only when the network connection was broken? The reporters claim having no problems with their internet connection, but it's not something I can verify.

There is no particular pattern when the error occurs, other then it's 'somewhere in the middle' (so anyway, random).