--- a/ProjectDefinition.st	Mon Sep 22 15:45:15 2008 +0200
+++ b/ProjectDefinition.st	Mon Sep 22 16:04:33 2008 +0200
@@ -162,8 +162,12 @@
         |def|
 
         def := self definitionClassForPackage:eachPackageID.
-        def effectivePreRequisites do:[:eachPrerequisitePackageID|
-            orderedTuples add:(Array with:eachPrerequisitePackageID with:eachPackageID).
+        def isNil ifTrue:[
+            Transcript showCR:'Warning: no definition class for package: ',eachPackageID
+        ] ifFalse:[
+            def effectivePreRequisites do:[:eachPrerequisitePackageID|
+                orderedTuples add:(Array with:eachPrerequisitePackageID with:eachPackageID).
+            ]
         ].
     ].
 
@@ -4089,7 +4093,7 @@
 !ProjectDefinition class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/ProjectDefinition.st,v 1.200 2008-09-22 13:45:15 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/ProjectDefinition.st,v 1.201 2008-09-22 14:04:33 cg Exp $'
 ! !
 
 ProjectDefinition initialize!