Throw error if the worker thread creation fails

[kateinoigakukun]

use-sites still can fallback to other task executors, so it should be a recoverable error rather than a fatal error.

[github-actions]

Time Change: -1ms

Total Time: 9,743ms

Test name	Duration	Change
Serialization/JavaScript function call through Wasm import with int	23ms	+2ms (7%)	🔍

View Unchanged

Test name	Duration	Change
Serialization/JavaScript function call through Wasm import	24ms	+0ms
Serialization/JavaScript function call from Swift	129ms	+5ms (3%)
Serialization/Swift Int to JavaScript with assignment	326ms	-0ms
Serialization/Swift Int to JavaScript with call	975ms	+3ms (0%)
Serialization/JavaScript Number to Swift Int	259ms	-1ms (0%)
Serialization/Swift String to JavaScript with assignment	403ms	-3ms (0%)
Serialization/Swift String to JavaScript with call	1,058ms	+2ms (0%)
Serialization/JavaScript String to Swift String	3,687ms	-25ms (0%)
Object heap/Increment and decrement RC	2,818ms	+9ms (0%)

View Baselines

Test name	Duration
Serialization/Call JavaScript function directly	10ms
Serialization/Assign JavaScript number directly	7ms
Serialization/Call with JavaScript number directly	8ms
Serialization/Write JavaScript string directly	7ms
Serialization/Call with JavaScript string directly	8ms