2 files changed, 3 insertions, 0 deletions
diff --git a/chapter21/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter21/src/main/java/com/seaofnodes/simple/node/LoadNode.java
index 80bf989c..c8cca355 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/node/LoadNode.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/node/LoadNode.java
@@ -139,6 +139,7 @@ public class LoadNode extends MemOpNode {
     private Node zero(NewNode nnn) {
         TypeStruct ts = nnn._ptr._obj;
         Type zero = ts._fields[ts.findAlias(_alias)]._type.makeZero();
+        assert zero.isa(_type); // Catch an uninitialized non-null field
         return castRO(new ConstantNode(zero).peephole());
     }
 
diff --git a/chapter21/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/chapter21/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index 8878193c..f15ff9bb 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -106,6 +106,8 @@ public class StoreNode extends MemOpNode {
     public Parser.ParseException err() {
         Parser.ParseException err = super.err();
         if( err != null ) return err;
+        if( ptr()._type == Type.TOP )
+            return null; // Dead store
         TypeMemPtr tmp = (TypeMemPtr)ptr()._type;
         if( tmp._obj.field(_name)._final && !_init )
             return Parser.error("Cannot modify final field '"+_name+"'",_loc);