Some commands of `bitcoin-tx` accept an index of an existing input/output, e.g. `delin` or `delout`.  And while the index is checked for being out-of-bounds, garbage (non-numeral characters) are happily accepted.  All of the following are fine:

    $ bitcoin-tx -create outaddr=1:1M72Sfpbz1BPpXFHz9m3CdqATR44Jvaydd delout=
    $ bitcoin-tx -create outaddr=1:1M72Sfpbz1BPpXFHz9m3CdqATR44Jvaydd delout=foobar
    $ bitcoin-tx -create outaddr=1:1M72Sfpbz1BPpXFHz9m3CdqATR44Jvaydd delout=0bla

I think all of them should throw an error instead of silently treating the index as zero.

The reason for this is that internally, `atoi` is called - and that by design discards anything after the first non-numeric character (and may just return zero if there are no numerals at all).

A possible fix would be to use `strtol` instead and to verify that the returned `endptr` is actually the end of the input string.  Alternatively, one could convert the integer back to a string and require that it matches the input string exactly.
std::string arg = argv[i];
            std::string key, value;
            size_t eqpos = arg.find('=');
            if (eqpos == std::string::npos)
                key = arg;
            else {
                key = arg.substr(0, eqpos);
                value = arg.substr(eqpos + 1);
            }
            MutateTx(tx, key, value);
        }
        OutputTx(tx);
    }
    catch (const boost::thread_interrupted&) {
        throw;
    }
    catch (const std::exception& e) {
        strPrint = std::string("error: ") + e.what();
        nRet = EXIT_FAILURE;
    }
    catch (...) {
        PrintExceptionContinue(nullptr, "CommandLineRawTx()");
        throw;
    }
    if (strPrint != "") {
        fprintf((nRet == 0 ? stdout : stderr), "%s\n", strPrint.c_str());
    }
    return nRet;
}
int main(int argc, char* argv[])