WebGL Rendering Context - Fixed unnecessary unwrap calls for every send

[mrkajetanp]

WebGL Rendering Context

• replaced unwrap() calls every send to ipc_renderer with if .. is_err()
• if error occurs, added a warning - "WebRenderer is unavailable!"
• functions will immediately return after the warning

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• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix #16021 (github issue number if applicable).

• There are tests for these changes OR
• These changes do not require tests because _____
  I think they don't require additional tests because they're just meant to reduce possible thread panics if WebRenderer is not available for some reason.

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This change is 

[highfive]

Thanks for the pull request, and welcome! The Servo team is excited to review your changes, and you should hear from @metajack (or someone else) soon.

[highfive]

Heads up! This PR modifies the following files:

• @KiChjang: components/script/dom/webglrenderingcontext.rs
• @fitzgen: components/script/dom/webglrenderingcontext.rs
• @emilio: components/script/dom/webglrenderingcontext.rs

[highfive]

Warning

• These commits modify script code, but no tests are modified. Please consider adding a test!

[jdm]

@bors-servo: try

[bors-servo]

⌛ Trying commit 577e4ad with merge ab93400...

[metajack]

The semantic change here is that previously these unwraps would panic if there was an error, but now we simply warn. Probably @glennw should weigh in on whether panics are appropriate or if we can relax them to warnings.

[jdm]

Don't we want Servo to be able to continue displaying the page even if something goes wrong in the WebGL rendering thread?

[metajack]

We do, but if the end result of this is that the renderer never recovers, it's not really much of an improvement. I haven't gone to look, but that part is already there, then the panics would indeed be unnecessary.

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel-css, linux-rel-wpt, mac-dev-unit, mac-rel-css, mac-rel-wpt1, mac-rel-wpt2, windows-msvc-dev
State: approved= try=True

[mrkajetanp]

Well I guess if there are functions in which an error results in the renderer not being able to recover, we could panic!() instead of return in them.
I'm no expert but I think that even if that's the case for some functions, it doesn't apply to all of them.

[KiChjang]

@bors-servo try-

[KiChjang]

@bors-servo r- try- clean

[sviter]

What is the status of this PR?

[jdm]

It sounds like this change is not desired until we support recreating a failed renderer, unfortunately.