Release v1.2.3

null values will no longer be tried to send but give error message (Sentry IOBROKER-S7-8)
Prevent some more crash cases (IOBROKER-S7-1, IOBROKER-S7-9, IOBROKER-S7-E, IOBROKER-S7-F, IOBROKER-S7-G)