@uppy/aws-s3: missing eTag prevents file upload completion when using GCS

[pxue]

Initial checklist

• I understand this is a bug report and questions should be posted in the Community Forum
• I searched issues and couldn’t find anything (or linked relevant results below)

Link to runnable example

No response

Steps to reproduce

1. set up AwsS3 but use GCS as drop-in replacement
2. upload from local file

Expected behavior

Upload expects to complete successfully AND event completes

Actual behavior

Upload completes fine but onComplete is not called because missing etag shortcircuits the function

From GCS:
https://cloud.google.com/storage/docs/metadata

Etag is not expected to return unless using XML API. While I can copy/paste the provider, this should work with GCS as well.

[pxue]

The intermediate fix is to just clone the entire AwsS3 provider and implement it myself

instead of parsing eTag / location from the header, it's parsed from the response body

  static parseXMLResponse(xml: string | null) {
    if (!xml) {
      return {};
    }
    const parser = new DOMParser();
    const doc = parser.parseFromString(xml, "application/xml");
    const etag = doc.querySelector("PostResponse ETag")?.textContent;
    const location = doc.querySelector("PostResponse Location")?.textContent;
    return { etag, location };
  }