Fixed codegen for empty (mapped) action block.
Although empty blocks are useless in practice, they may occur (and do occur in tests)
"{ Package: 'stx:goodies/petitparser/compiler' }"
"{ NameSpace: Smalltalk }"
PPCNilNode subclass:#PPCSentinelNode
instanceVariableNames:''
classVariableNames:''
poolDictionaries:''
category:'PetitCompiler-Nodes'
!
PPCSentinelNode class instanceVariableNames:'Instance'
"
No other class instance variables are inherited by this class.
"
!
!PPCSentinelNode class methodsFor:'as yet unclassified'!
instance
^ Instance ifNil: [ Instance := self basicNew ]
! !