var brokenJson = function (url) {
var responseCopy;
return fetch(url)
.then(function (response) {
responseCopy = response.clone();
return response.json();
}).catch(function (err) {
if (err instanceof SyntaxError) {
return responseCopy.text()
.then(function(text) {
console.error(text);
throw err;
});
}
else {
throw err;
}
}).then(function (json) {
// do things
});
};