Fixed unwrap on None when importing embedded assets #31875

Job	Run time
build (windows-latest)	6m 23s
check-bevy-internal-imports	10s
build (ubuntu-latest)	1m 49s
check-doc	8m 13s
build (macos-latest)	2m 51s
check-missing-examples-in-docs	52s
ci	1m 32s
miri	5m 57s
run-examples-on-windows-dx12	18m 45s
check-missing-features-in-docs	59s
check-compiles	1m 59s
markdownlint	1m 28s
msrv	48s
build-wasm	57s
	52m 43s

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