I think this is comparable to checking a property on a form that doesn't exist. Vartype tries to find the form first before checking the property, and
fails if it doesn't find it. On your example it tries finding the array element
before doing the check on the element.
Good tip here might be, creating your own function and using the type() or vartype() function in it, it should solve the problem.

FUNCTION checkVAR
LPARAMETER voVar, lcType
IF VARTYPE(voVar) = ALLTRIM(UPPER(lcType))
IF ISNULL(voVar)
RETURN .F.
ELSE
RETURN .T.
ENDIF
ELSE
RETURN .F.
ENDIF

Anyway it's probably some kind of notreallythewayitshouldbeism.

Greetings,
Jeroen