UNKNOWN_ERROR LHRs cause Rendering Failure

[exterkamp]

Provide the steps to reproduce

Try to render an UNKNOWN ERROR LHR from PSI. Seems like we set configSettings and other things to null instead of filling them in (requestedUrl is null even though we know what url was requested). This causes renderer problems since it expects some things to exist.

What is the current behavior?

Uncaught TypeError: Cannot read property 'channel' of null

What is the expected behavior?

Rendering a failed report.

@patrickhulce ideas for this? I was thinking we populate most of the LHR in lr-entry before bailing with an UNKNOWN ERROR.

[brendankenny]

Try to render an UNKNOWN ERROR LHR from PSI. Seems like we set configSettings and other things to null instead of filling them in (requestedUrl is null even though we know what url was requested). This causes renderer problems since it expects some things to exist.

This was by design, though (#6014). The result was never supposed to be passed into the report renderer (it's nothing close to an LHR), it was only to satisfy the API needing an object with a top-level runtimeError.

lighthouse/clients/lightrider/lightrider-entry.js

Lines 74 to 89 in 959c499

	} catch (err) {
	// If an error ruined the entire lighthouse run, attempt to return a meaningful error.
	let runtimeError;
	if (!(err instanceof LHError) || !err.lhrRuntimeError) {
	runtimeError = {
	code: LHError.UNKNOWN_ERROR,
	message: `Unknown error encountered with message '${err.message}'`,
	};
	} else {
	runtimeError = {
	code: err.code,
	message: err.friendlyMessage ?
	`${err.friendlyMessage} (${err.message})` :
	err.message,
	};
	}

I was thinking we populate most of the LHR in lr-entry before bailing with an UNKNOWN ERROR.

I think this is the real phrasing of the issue. Current behavior is/was WAI. If the intent should instead be to always get an LHR back, lightrider-entry.js will need to recreate an LHR at that point.

[exterkamp]

Brendan has convinced me that this is WAI for Lighthouse, and needs to be handled client side. I will move this to track internally for PSI/LR.