Regression in version @azure/functions:4.7.3 due to undici 7.x upgrade.

[swapnil-nagar]

Description:

This issue is to track a regression introduced in version 4.7.3 of the @azure/functions Node.js library.

Problem

Version 4.7.3 of @azure/functions upgraded the undici dependency from 5.x to 7.x because undici@5.x reached EOL on April 30, 2024. However, this change introduces a breaking behavior:

undici@7.x requires Node.js 20 or later

As a result, apps still running on Node.js <= 18 and using @azure/functions@4.7.3 will fail with the following runtime error:

Result: Failure
Exception: value.toWellFormed is not a function
Stack: TypeError: value.toWellFormed is not a function
at webidl.converters.USVString (node_modules/undici/lib/web/webidl/index.js:578:18)

Current Mitigation

The @azure/functions@4.7.3 package has now been deprecated on npm to prevent further adoption.

Apps should pin to an older version of @azure/functions (e.g., 4.7.2).

Affected apps need to be rebuilt and redeployed to ensure downgrade is applied.

[BridgeAR]

This fixes it: #357

[timtucker-dte]

Again, this seems like the correct answer isn't to revert to the older version of Undici -- it's to move @azure/functions forward to drop support for Node 18, matching the current list of supported platforms & other Azure SDKs.

We're already including Undici 7 in our app and it was great to finally not have the extra weight of including 2 versions of Undici.

Presumably that means upping the major version to 5.x -- and if there's going to be a new version with breaking changes, that's a good time to finally tackle #269 and bump up the Typescript version to 5.