replace cross-fetch with isomorphic-unfetch

[wentokay]

Problem

cross-fetch injects XMLHttpRequest into the bundled outputs of web3.js and this is incompatible with workers, so web3.js cannot run inside web or service workers.

This also means it can't run inside server-based workers like 'cloudflare workers'

As a result it might be incompatible with some of the suggested deployment paths for popular tools like https://remix.run

Finally it is also adding extra unnecessary bloat into browsers where fetch is already supported e.g. var xhr = new XMLHttpRequest(); in https://cdn.jsdelivr.net/npm/@solana/web3.js@1.43.1/lib/index.browser.esm.js

Summary of Changes

replace cross-fetch with isomorphic-unfetch ponyfill

Compatibility

	node	browser	worker
fetch	❌	✅	✅
cross-fetch (2.8kB)	✅	✅	❌
isomorphic-unfetch (591B)	✅	✅	✅

Tested as working for

• node (commonjs)
• node (esmodules)
• browser <script type="text/javascript">
• browser <script type="module">
• inside a serviceworker

by running

yarn build && yarn link in this PR branch

then

yarn link @solana/web3.js & running each of the package.json scripts in https://github.com/wentokay/unfetch-test

related:

• feat: add fetch option to support cloudflare worker #21388
• feat: Rewrite to use fetch stytchauth/stytch-node#121
• Cross-fetch is not usable in service workers lquixada/cross-fetch#78

[codecov]

Codecov Report

Merging #25500 (6a56e9e) into master (f9f6b94) will decrease coverage by 6.6%.
The diff coverage is n/a.

❗ Current head 6a56e9e differs from pull request most recent head cd34f4d. Consider uploading reports for the commit cd34f4d to get more accurate results

@@             Coverage Diff             @@
##           master   #25500       +/-   ##
===========================================
- Coverage    82.0%    75.3%     -6.7%     
===========================================
  Files         655       39      -616     
  Lines      171822     2337   -169485     
  Branches      335      335               
===========================================
- Hits       140972     1762   -139210     
+ Misses      30734      459    -30275     
  Partials      116      116               

[wentokay]

I was unsure what to do with two lockfiles so I ran both yarn install and npm install although perhaps this is problematic?

[t-nelson]

whoever reviews this, please be vigilant of supply chain attacks. we don't generally accept this type of change from external contributors

[steveluscher]

We’re actually going to eliminate the fetch polyfill entirely and ask that folks using Node older than 17.5 to bring their own polyfill. See #25014.

[steveluscher]

For instance, for Remix specifically: https://remix.run/docs/styling/v1/other-api/node

[steveluscher]

Thanks for opening this PR though! Super good call out about service workers.