Rule with lastUpdate fails with null?

Setup, Configuration and Use Scripts & Rules
1

I have a rule where I’m looking on the time of the last update. I always get the following error:

2018-03-02 18:41:19.248 [ERROR] [ntime.internal.engine.RuleEngineImpl] - Rule 'BLNet Raw auswerten': cannot invoke method public abstract long org.joda.time.ReadableInstant.getMillis() on null

I toggled the value of the item several times to be sure that there is a last value, but the error still occurs.

The code where it happens is in the first code line:

// nach ca. 60 Minuten, danach alle 24 Stunden Nachricht versenden
val LastReset = swi_Heiz_ResetBLNet.lastUpdate.getMillis
val Jetzt = now.millis
val Number Diff = Minutes::minutesBetween(new DateTime(LastReset), new DateTime(Jetzt)).getMinutes()
if (Diff.intValue % (24 * 60) == 60)
	sendTelegram("HausWartung", "BLnet benötigt Reset!")

The Item is defined as

Switch	swi_Heiz_ResetBLNet		"BLnet: Reset nötig"		<none>		(gRestoreOnStartup)

The group gRestoreOnStartup defines persistence via mapdb. This works for other items without problems.

Can you help me?

2

Is mapdb the default persistence service? otherwise you will have to use

val LastReset = swi_Heiz_ResetBLNet.lastUpdate("mapdb").millis

instead.

EDIT: Please be aware that, according to good old Designer, it’s .millis, not .getMillis

3

MapDB is defined as standard, but I also tried with the version you proposed. it does not make any difference.
Also if I use .millis or .getMillis.