Fails to parse `let mapleader`

[jonhoo]

$ cargo r --release -- --file (echo 'let mapleader = "\\<Space>"' | psub) --outdir converted
    Finished release [optimized] target(s) in 0.03s
     Running `/home/jon/.cargo-target/release/vim9jit --file /tmp/.psub.RwbSA8XMXW --outdir converted`
thread 'main' panicked at '
Failed to parse command.
Current Commands:Program {
    commands: [],
}.
Error: No prefix function: Parser {
    lexer: Lexer { position: 27, read_position: 28, ch: None },
    token_buffer: RefCell {
        value: [
            Token(Equal, "=", (0,14)->(0,15)),
            Token(DoubleQuoteString, "\\<Space>", (0,17)->(0,24)),
            Token(EndOfLine, "\n", (0,26)->(0,26)),
        ],
    },
}', crates/vim9-parser/src/lib.rs:2559:29
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace