ResponseEmitter::emit() breaking Gravity Forms "Page" confirmations

[brittanycresswell]

After upgrading to v8.2, form submissions using Gravity Forms "Page" confirmation type result in a 500 error due to an EmitterException.
ResponseEmitter::emit() correctly guards against headers_sent() but doesn't guard against the case where the output buffer has content but headers haven't been sent yet. SapiEmitter::assertNoPreviousOutput() throws in this scenario because ob_get_level() > 0 && ob_get_length() > 0.

Environment: Lumberjack v8.2, Gravity Forms, WordPress 6.9.4

Here is the error from my php logs:
PHP Fatal error: Uncaught Laminas\HttpHandlerRunner\Exception\EmitterException:
Output has been emitted previously; cannot emit response in
/vendor/laminas/laminas-httphandlerrunner/src/Exception/EmitterException.php:21

[tommitchelmore]

@brittanycresswell good catch, thank you. We'll work on a fix for this (see #73).

[tommitchelmore]

Hi @brittanycresswell,

We've pushed a patch for this, and I'll tag it shortly as v8.2.1. Please do let us know if that resolves the issue.

Update: We have some more changes to release - we'll include this in the upcoming v8.3.0 tag that we'll do this week.

If you get any more issues, feel free to let us know on the Lumberjack Slack Channel in case we miss an issue being raised.

Best,
Tom