.

go/zodb/connection.go

@@ -155,6 +155,10 @@ func (conn *Connection) get(class string, oid Oid) (IPersistent, error) {
 	}
 	if obj == nil {
 		obj = newGhost(class, oid, conn)
+		//if obj == nil {
+		//	conn.objmu.Unlock()
+		//	return nil, fmt.Errorf("get %s: class %q not supported", Xid{conn.at, oid}, class)
+		//}
 		conn.objtab[oid] = weak.NewRef(obj)
 	} else {
 		checkClass = true

go/zodb/persistent.go

@@ -383,6 +383,7 @@ func newGhost(class string, oid Oid, jar *Connection) IPersistent {
 	var xpobj reflect.Value // *typ
 	zc := classTab[class]
 	if zc == nil {
+		//return nil
 		zc = brokenZClass
 		xpobj = reflect.ValueOf(&Broken{class: class})
 	} else {
@@ -439,6 +440,11 @@ func (b *brokenState) SetState(state *mem.Buf) error {
 	return nil
 }
 
+// XXX how to print zodb.Broken("BTrees.IOBTree.IOBTree"), but not long noise for types that don't define GoString?
+func (b *Broken) GoString() string {
+	return fmt.Sprintf("&zodb.Broken(%q)", b.class)
+}
+
 // brokenZClass is used for Persistent.zclass for Broken objects.
 var brokenZClass = &zclass{
 	class:     "",