Warning messages from indexOf function

[rjwills28]

When using the indexOf() formula function we see the following warning message:

WARNING [org.csstudio.apputil.formula] Formula function error for indexOf(current:test2)
java.lang.Exception: Function indexOf requires an enum argument [VDouble[NaN, NONE(NONE) - None, 2026-03-30T14:28:43.178639698Z]]
	at org.csstudio.apputil.formula.enums.IndexOfFunction.compute(IndexOfFunction.java:64)
	at org.csstudio.apputil.formula.node.SPIFuncNode.eval(SPIFuncNode.java:54)
	at org.csstudio.apputil.formula.Formula.eval(Formula.java:181)
	at org.phoebus.pv.formula.FormulaPV.<init>(FormulaPV.java:59)
	at org.phoebus.pv.formula.FormulaPVFactory.createPV(FormulaPVFactory.java:31)
	at org.phoebus.pv.PVPool.createPV(PVPool.java:223)
	at org.phoebus.pv.PVPool.lambda$getPV$0(PVPool.java:214)
	at org.phoebus.pv.RefCountMap.createOrGet(RefCountMap.java:101)
	at org.phoebus.pv.PVPool.getPV(PVPool.java:214)

This is because the PV has not yet connected and as soon as it does we get a valid value. It seems like we shouldn't be trying to evaluate the formula expression until the PV has connected.

I am wondering whether we really need to call the formula.eval() here, which occurs before trying to connect to the PV? Could we remove these two lines and only call eval() after trying to connect to the PV?

The other option would be to catch the case where the PV is not disconnected in the indexOf code and not throw the exception in this case?

[shroffk]

There are use cases where we might want to value to be processed even if the underlying PV's are not connected. This would also apply to cases where we have formula function with no PV's.

I agree that we need better error handling and reporting as this case shows...and I think your suggestion of catching the exception and checking connection state before throwing the exception makes sense.

[rjwills28]

Thanks for the input @shroffk - please see PR with fix: #3756.

[rjwills28]

PR merged - closing issue. Thanks all.