@uppy/xhr-upload: do not throw when res is missing url

[Murderlon]

Closes #5131

Accidentally introduced a breaking change. I thought sending back a url is mandatory and that's why we have things like getResponseData and responseUrlFieldName so you can get it in a flexible way. But it seems it wasn't needed and people didn't do it and now their uploads stopped working.

[github-actions]

Diff output files

diff --git a/packages/@uppy/xhr-upload/lib/index.js b/packages/@uppy/xhr-upload/lib/index.js
index cf9da5c..b70a498 100644
--- a/packages/@uppy/xhr-upload/lib/index.js
+++ b/packages/@uppy/xhr-upload/lib/index.js
@@ -177,12 +177,7 @@ export default class XHRUpload extends BasePlugin {
             throw new NetworkError(res.statusText, res);
           }
           const body = this.opts.getResponseData(res.responseText, res);
-          const uploadURL = body[this.opts.responseUrlFieldName];
-          if (typeof uploadURL !== "string") {
-            throw new Error(
-              `The received response did not include a valid URL for key ${this.opts.responseUrlFieldName}`,
-            );
-          }
+          const uploadURL = body == null ? void 0 : body[this.opts.responseUrlFieldName];
           for (const file of files) {
             this.uppy.emit("upload-success", file, {
               status: res.status,

[mifi]

Suggested change

	const uploadURL = body?.[this.opts.responseUrlFieldName] as
	| string
	| undefined
	const uploadURL = body[this.opts.responseUrlFieldName]
	if (!(typeof uploadURL === 'string' || uploadURL == null)) {
	throw new Error(
	`The received response did not include a valid URL for option responseUrlFieldName ${this.opts.responseUrlFieldName}`,
	)
	}

[Murderlon]

As you can read in the issue and my comment, the whole point is that this should not be required.

[mifi]

yes, and i think my suggested code is a safer way to check that rather than using a blind type assertion

[Murderlon]

This PR removes the error, an undefined url is allowed. It was a breaking change to throw an error. You suggestion makes the exact same again as before this PR.

[mifi]

i'm not sure how my suggestion would make it the exact same as before this PR, as i added a check that allows undefined and null (== operator).

If uploadURL is undefined, !(typeof uploadURL === 'string' || uploadURL == null) evaluates to false, hence it will not throw the error.