sort: fix panic when collator not available in worker threads #941

Job	Run time
L10n/Fluent Syntax Check	17s
L10n/French Integration Test	1m 46s
L10n/Multi-call Binary Install Test (ubuntu-latest, feat_os_unix)	3m 59s
L10n/Locale Support Verification	7m 22s
L10n/Build and Test (macos-latest, feat_os_macos)	7m 35s
L10n/Locale Embedding - Cat Utility	48s
L10n/Locale Embedding - Ls Utility	1m 17s
L10n/Clap Error Localization Test	2m 17s
L10n/Embedded Locale Regression Test	2m 27s
L10n/Locale Embedding - Multicall Binary	2m 51s
L10n/Multi-call Binary Install Test (macos-latest, feat_os_macos)	5m 56s
L10n/Build and Test (ubuntu-latest, feat_os_unix)	3m 40s
L10n/Installation Test (Make & Cargo) (ubuntu-latest, feat_os_unix)	6m 13s
L10n/Installation Test (Make & Cargo) (macos-latest, feat_os_macos)	10m 22s
L10n/Build and Test (windows-latest, feat_os_windows)	9m 0s
L10n/Locale Embedding - Cargo Install	2m 41s
L10n/Locale Embedding Regression Test	3s
	1h 8m 34s

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