Check for unknown types in AtomicType translation. 
Check for unknown types in AtomicType translation. 

Let $x := $x now correctly fails

28msec/zorba,bgarrels/zorba,bgarrels/zorba,bgarrels/zorba,28msec/zorba,28msec/zorba,cezarfx/zorba,bgarrels/zorba,bgarrels/zorba,cezarfx/zorba,cezarfx/zorba,bgarrels/zorba,28msec/zorba,28msec/zorba,cezarfx/zorba,cezarfx/zorba,cezarfx/zorba,bgarrels/zorba,28msec/zorba,28msec/zorba,cezarfx/zorba,cezarfx/zorba,cezarfx/zorba,bgarrels/zorba,cezarfx/zorba,28msec/zorba,28msec/zorba