double sign error fixed

[aviral10x]

    mapping list_signed: Person => bool;

    struct Person {
        signer: address,
        proposal: Proposal
    }
    
    




    finalize sign(caller: address, proposal: Proposal) {
        assert(Mapping::get(signers, caller));
        Mapping::get(list_signed, Person { signer: caller, proposal: proposal });
        let signatures: u64 = Mapping::get_or_use(proposals, proposal, 0u64);
        Mapping::set(proposals, proposal, signatures + 1u64);
        Mapping::set(list_signed, Person { signer: caller, proposal: proposal }, true);
    }