Error: Module:Sandbox/Kotz/G:5: attempt to index field 'wikibase' (a nil value)


function getProperty( entityName, propertyName )
    local entity
	mw.log ("entityName=" .. entityName)
	mw.log ("propertyName=" .. propertyName)
	if (entityName) then entity=mw.wikibase.getEntityObject(); else entity=mw.wikibase.getEntityObject(entityName) end
	if (entity) then
		mw.log(entity)
    	if (entity.claims) then
		    local property = entity.getProperties()
		    if (property) then
		    	return property
		    end
		end
	end
	return
end
 
function property( frame )
    local status, result = pcall(getProperty, string.upper(frame.args[1]), string.lower(frame.args[2]))
    return (status and '' or 'Error: ') .. (result or '')
end
 
return {
    property = property,
    Property = property
}