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.
{
    
    size_t pos = strInput.find(':');
    if ((pos == std::string::npos) ||
        (pos == 0) ||
        (pos == (strInput.size() - 1)))
        throw std::runtime_error("Register input requires NAME:VALUE");
    std::string key = strInput.substr(0, pos);
    std::string valStr = strInput.substr(pos + 1, std::string::npos);
    RegisterSetJson(key, valStr);
}
static void RegisterLoad(const std::string& strInput)
{
    
    size_t pos = strInput.find(':');
    if ((pos == std::string::npos) ||
        (pos == 0) ||
        (pos == (strInput.size() - 1)))
        throw std::runtime_error("Register load requires NAME:FILENAME");
    std::string key = strInput.substr(0, pos);
    std::string filename = strInput.substr(pos + 1, std::string::npos);
    FILE *f = fopen(filename.c_str(), "r");
    if (!f) {
        std::string strErr = "Cannot open file " + filename;
        throw std::runtime_error(strErr);
    }
    
    std::string valStr;
    while ((!feof(f)) && (!ferror(f))) {