[Res] groovy code works externally but fails in SoapUI Pro

I have groovy code that runs find externally but fails with the following error inside SoapUI Pro.
I'm using SoapUI Pro v4.6.4


Thu Apr 10 10:55:14 EDT 2014:ERROR:java.lang.NullPointerException: Cannot execute null+null
java.lang.NullPointerException: Cannot execute null+null
at org.codehaus.groovy.runtime.NullObject.plus(NullObject.java:121)
at org.codehaus.groovy.runtime.NullObject$plus.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
at org.codehaus.groovy.runtime.callsite.NullCallSite.call(NullCallSite.java:32)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at CommonAssertions$_luhnChecksum_closure5.doCall(Script8.groovy:242)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:909)
at groovy.lang.Closure.call(Closure.java:411)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.eachWithIndex(DefaultGroovyMethods.java:1317)
at org.codehaus.groovy.runtime.dgm$153.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at CommonAssertions.luhnChecksum(Script8.groovy:238)


The error method points to the conditional assignment statement - again this code runs fine
outside SoapUI. See code below.
Has anyone run into similar problems? Any ideas of things to try?




def luhnChecksum(def number) {
log.info(" luhnCS: number: " + number)
int total
(number as String).reverse().eachWithIndex { ch, index ->
def digit = Integer.parseInt(ch)
log.info(" luhnCS: digit: " + digit + " ch: " + ch + " index: " + index)
// may need to add '\' in front of question mark for library to be parsed w/o error
fails ==> total += (index % 2 == 0) ? digit : [0, 2, 4, 6, 8, 1, 3, 5, 7, 9][digit]
// does this assume the length of a card number
}
def checksum = total % 10
log.info(" luhnCS: checksum: " + checksum)
return checksum
}