Unable to report a metric with value of 0

[SlicedSilver]

zabbix-promise/lib/utils.js

Line 39 in 2bd01c2

if (!options.value) throw new Error('"value" is missing')

Currently it is not possible to report a metric of zero because the library checks the value as shown above. Shouldn't the library rather check if the value is undefined, null, or an empty string?

This would allow the library to report values of zero.

if (options.value == undefined || options.value === '') throw new Error('"value" is missing')

Happy to submit a PR.