WalletCore Swallow exceptions , Make debugging much harder

[johnnyluo]

To be honest , I am not sure this should be a bug or a feature request
Describe the bug
I have been using WalletCore as a library in my own wallet app, and I am using it in IOS, swift and xcode, so I have been use it quite a lot recently , and find out WalletCore usually swallow all the exceptions, let me give you an example.
The follow function , it catch all exceptions , and return empty instead, there is no logging , nothing

TWData *_Nonnull TWTransactionCompilerCompileWithSignatures(enum TWCoinType coinType, TWData *_Nonnull txInputData, const struct TWDataVector *_Nonnull signatures, const struct TWDataVector *_Nonnull publicKeys) {
    Data result;
    try {
        assert(txInputData != nullptr);
        const Data inputData = data(TWDataBytes(txInputData), TWDataSize(txInputData));
        assert(signatures != nullptr);
        const auto signaturesVec = createFromTWDataVector(signatures);
        assert(publicKeys != nullptr);
        const auto publicKeysVec = createFromTWDataVector(publicKeys);

        result  = TransactionCompiler::compileWithSignatures(coinType, inputData, signaturesVec, publicKeysVec);
    } catch (...) {} // return empty
    return TWDataCreateWithBytes(result.data(), result.size());
}

This make debug issues quite hard , at least it cost me a least more than a day to figure out why the function return empty bytes.

• For Bitcoin , the signature need to be in DER format , otherwise it return empty, and no error ,
• For ETH , the signature need to R+S+RecoveryID , it is not DER format
• For ETH , the public key , you don't have to pass in the public key , or if you do want to , make sure the public key is in secp256k1Extended

If the function can bubble up the exception , or error message will greatly help debugging.
I raised it here in hope we could make it better

To Reproduce

Expected behavior
bubble up the exceptions

Screenshots

Additional context

[satoshiotomakan]

Hi @johnnyluo, that's also right. We introduced an error system in Rust, but it's not available in C++ FFI yet.
Hope we have time this year to work on it to improve UX.