Counter64 stringified as '[object Object'] when serialized

[infrared]

From one of my traps, one of the varbinds had a string_value as '[object Object]'

 { oid: '1.3.6.1.4.1.9.9.383.1.1.1.0',
      typename: 'Counter64',
      value: { lo: 2974423586, hi: 1588 },
      string_value: '[object Object]' },

From the tcpdump:

   .1.3.6.1.4.1.9.9.383.1.1.1.0=1355944442194980864.000771

Please let me know what other information I can provide to assist.

[ghost]

This requires the analogue of sprintf("%llu", (uint64_t)whatever) without having access to any integer operations capable of supporting more than 32-bit quantities. Remarkably, this seems like an unsolved problem in the Node.js ecosystem, at least without going native. node-int64 stringifies anything that uses more than 53 bits as 'Infinity', which is really unhelpful. int64-native would work here but I'd rather not introduce that dependency if we can avoid it, so I implemented the necessary pieces for 64-bit integer decoding in Javascript.
With this change, I now do:

# snmptrap -v 2c -c public localhost trapoid 1.3.6.1.4.1.9926.1.21.1.7.3 1.3.6.1.4.1.9926.1.21.1.4.1.1.14 i 2 1.3.6.1.4.1.9926.1.21.1.4.1.1.10 C 2394872985723948

and get

…
        { oid: '1.3.6.1.4.1.9926.1.21.1.4.1.1.10',
          typename: 'Counter64',
          value: { _hi: 557599, _lo: 3516441644 },
          string_value: '2394872985723948' } ] } }

Test cases added, 0.1.6 released as well. Thanks for the report, though I must say that I did not expect this simple issue to require this much work!