Request fails when using non-text responseType

[qgustavor]

Mithril Version: v2.0.0-rc.3

When using m.request with responseType to request non-text data (like blobs and arraybuffers) it fails with a DOMException as it tries to read .responseText and it's only valid for text content.

Expected Behavior

Requesting data using responseType set to any valid value should not throw an error and the response could be accessed someway (on v2.0.0-rc.1 it could be accessed using extract).

Current Behavior

The request fails when responseType is set to valid values which aren't "text" or a empty string, like "arraybuffer" or "blob".

Possible Solutions

• Don't read xhr.responseText when extract is defined (restore v2.0.0-rc.1 behavior);
• Don't read xhr.responseText when responseType is not falsy or "text", instead read xhr.response. It allows using deserialize to handle non-text responses keeping the default xhr.status error handling (which is disabled when using extract).

Steps to Reproduce

m.request({
	url: "/some-url",
	responseType: "arraybuffer",
	extract: xhr => xhr.response
})

JSFiddle for v2.0.0-rc.1 and v2.0.0-rc.3

Context

I'm trying to request binary data using m.request.

Additional Information

Your Environment

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