Do not crash for zero expectations.

src/Znock/Znock.class.st

@@ -28,7 +28,7 @@ Znock >> baseFor: descriptor [
 
 { #category : #operations }
 Znock >> consumeExpectationFor: aZnockClient [ 
-	^ expectations
+	^ self expectations
 		detect: [ :one | aZnockClient matches: one ]
 		ifFound: [ :one | expectations remove: one. one ]
 		ifNone: [ nil ]