if matches!(claims.exp, TryParse::Parsed(exp) if options.validate_exp
        && exp - options.reject_tokens_expiring_in_less_than < now - options.leeway )

e.g. claims.exp can be "1" and pass the parse check but overflow in the calculation and lead to panic. stack trace below.

thread 'tokio-runtime-worker' panicked at /Users/0xd/.cargo/registry/src/index.crates.io-6f17d22bba15001f/jsonwebtoken-9.3.0/src/validation.rs:258:16:
attempt to subtract with overflow
stack backtrace:
0: rust_begin_unwind
at /rustc/25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04/library/std/src/panicking.rs:647:5
1: core::panicking::panic_fmt
at /rustc/25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04/library/core/src/panicking.rs:72:14
2: core::panicking::panic
at /rustc/25ef9e3d85d934b27d9dada2f9dd52b1dc63bb04/library/core/src/panicking.rs:144:5
3: jsonwebtoken::validation::validate
at /Users/0xd/.cargo/registry/src/index.crates.io-6f17d22bba15001f/jsonwebtoken-9.3.0/src/validation.rs:258:16
4: jsonwebtoken::decoding::decode
at /Users/0xd/.cargo/registry/src/index.crates.io-6f17d22bba15001f/jsonwebtoken-9.3.0/src/decoding.rs:267:13