wasmer_export_func_call 0 arg error

[liamappelbe]

wasmer_export_func_call in wasmer.hh reports "params ptr is null", even if params_len is 0. Seems like it should just ignore the params pointer if params_len is 0.

Currently I'm working around the issue like this:

std::vector<wasmer_value_t> params;
// Marshall params...

if (params.size() == 0) {
  // Wasmer requires that our params ptr is valid, even if params_len is 0.
  params.push_back(ToValueI32(0));
}

wasmer_value_t ret;
ThrowIfFailed(wasmer_export_func_call(
      fn->fn, &params[0], fn->wasm_args.size(), &ret, fn->has_ret ? 1 : 0)));

[Hywan]

You're right! See #756 for the fix. Thanks for the bug report :-).