The benchmark typecheck-nixpkgs-lib does not run

[Acaccia]

Describe the bug
As of now, there is a parsing error in the Nickel program used for this benchmark:

UnexpectedToken(RawSpan { src_id: FileId(8), start: ByteIndex(6569), end: ByteIndex(6577) }, ["\"\\\"\"", "\"..\"", "\";\"", "\"identifier\"", "\"m%\\\"\"", "\"}\""])] }'

To Reproduce
cargo bench --bench=typecheck-nixpkgs-lib

Expected behavior
The benchmark should run without issue.

Environment

• Version of the code: 793d3d2

[yannham]

Ah, #829 introduced a new keyword "optional", so the function with the same name causes a parse error. In the future we may want to parse metadata in a nicer way, without reserving tens of keywords, but for the time being, let's just rename this one.

[yannham]

Sorry, I meant #815, not 829.