ui.tools.debugger: don't throw an error if world has no children

diff --git a/basis/ui/tools/debugger/debugger.factor b/basis/ui/tools/debugger/debugger.factor
index f3f533e68170b0587b4daaa4c18bc790f04ceec0..2c653266e53ba863f7a85bd97360a1a317a9242b 100755 (executable)
--- a/basis/ui/tools/debugger/debugger.factor
+++ b/basis/ui/tools/debugger/debugger.factor
@@ -60,7 +60,8 @@ M: debugger focusable-child*
 
 GENERIC: error-in-debugger? ( error -- ? )
 
-M: world-error error-in-debugger? world>> gadget-child debugger? ;
+M: world-error error-in-debugger?
+    world>> children>> [ f ] [ first debugger? ] if-empty ;
 
 M: object error-in-debugger? drop f ;