Fix highlight js handling of missing languages #652

Job	Run time
mac-build (macos-14, arm64, 4.14.x)	8m 19s
linux-build (linux/arm64, linux-arm64, arm64, ubuntu-22.04-arm, false)	9m 32s
linux-build (linux/amd64, linux-amd64, x86_64, ubuntu-22.04, false)	8m 58s
mac-build (macos-15-intel, x86_64, 4.14.x)	17m 59s
release	0s
	44m 48s

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