Function __rerror_error_chain_length_shim 

#[doc(hidden)]
unsafe extern "C" fn __rerror_error_chain_length_shim<__ImplT: RError>(
    data: *mut c_void,
    argc: i32,
    argv: *const SEXP,
) -> SEXP

Method shim for RError::error_chain_length.

Converts SEXP arguments, calls the method, and returns SEXP result. Both Rust panics and R longjmps are caught via with_r_unwind_protect.