metrics return zeroes if the collector is unable to gather information

For instance, on NetBSD the format of /proc/stat is slightly different than that on Linux. Namely, it has only one space after "cpu", while the Linux version has two spaces, and we check for two spaces. The agent is thus unable to gather CPU statistics for all processors combined and returns zeroes for system.cpu.util[all,XXX,avgX] metrics. While the CPU problem on NetBSD can be easily fixed, can we make the agent return "ZBX_NOTSUPPORTED" in cases the collector cannot gather information for some reason?