completeErrorResponse function should stringify response before assigning it to Error in request

[boazblake]

Mithril.js version:
2.2.2
Browser and OS:
Chrome, Safari

The BAAS that I am using is sending an error object response that is not in the way completeErrorResponse is expecting.

It seems like completeErrorResponse is expecting the response to be a string but in my case the response is an object. Since new Error expects a string, wh3en completeErrorResponse assigns the error response to new error, it is no longer accessable, as when attempting to parse it, I get [object Object]

[boazblake]

On further logging, it seems that there is an exception that is not being handled properly at

mithril.js/request/request.js

Line 97 in 645cf66

try { message = ev.target.responseText }

This is the error:

responseText: [Exception: DOMException: Failed to read the 'responseText' property from 'XMLHttpRequest': The value is only accessible if the object's 'responseType' is '' or 'text' (was 'json'). at XMLHttpRequest.invokeGetter (<anonymous>:3:28) at xhr.onreadystatechange (http://localhost:3000/node_modules/.vite/deps/chunk-5DDGWUNV.js?v=2df1bbed:1525:19)]

and the value of the response parameter is: responseType: "json"

[boazblake]

I just tested with my changes by pointing my package json to the local, and I am wondering if this is the correct way to handle this issue, as I am now getting a string Error: {code:...., message:...}, so perhaps the rejection should not throw an Error if the response is JSON but the error object itself?

var completeErrorResponse = function () {
  if (ev.target.responseType == "json") {
	  reject(response)
  } else {
	  try { message = ev.target.responseText }
	  catch (e) { message = response }
	  var error = new Error(message)
	  error.code = ev.target.status
	  error.response = response
	  reject(error)
  }
}

[dead-claudia]

On further logging, it seems that there is an exception that is not being handled properly at

mithril.js/request/request.js

Line 97 in 645cf66

try { message = ev.target.responseText }

This is the error:

responseText: [Exception: DOMException: Failed to read the 'responseText' property from 'XMLHttpRequest': The value is only accessible if the object's 'responseType' is '' or 'text' (was 'json'). at XMLHttpRequest.invokeGetter (<anonymous>:3:28) at xhr.onreadystatechange (http://localhost:3000/node_modules/.vite/deps/chunk-5DDGWUNV.js?v=2df1bbed:1525:19[](http://localhost:3000/node_modules/.vite/deps/chunk-5DDGWUNV.js?v=2df1bbed:1525:19))]

and the value of the response parameter is: responseType: "json"

You're...kidding...

Is there seriously no way to get the original text as a string from an XHR independent of responseType?

[boazblake]

https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/responseText
no. If the value of responseType is not "" or "text" you cant read it as text.

I can update the PR to check for the string value of these types? https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/responseType

[kfule]

(memo)
The message parameter of the Error constructor requires a string type. Therefore, if responseType is not text nor empty, ToString() will set a meaningless message (e.g. [object Object]).

mithril.js/request/request.js

Lines 98 to 99 in 8b8abde

	catch (e) { message = response }
	var error = new Error(message)

On the other hand, since response(ev.target.response) is set in error.response, it seems possible to get the response data almost as is.

mithril.js/request/request.js

Lines 100 to 101 in 8b8abde

	error.code = ev.target.status
	error.response = response

[dead-claudia]

@kfule It's also worth noting that if the error is logged, you can still access the response property in the console and inspect it if you expand the stack trace.

Still not an ideal experience, but it is debuggable.

[kfule]

@dead-claudia Yes, I think so. It is debuggable.