Ensure that node pointer is valid before traversing.

src/apps/debugger/user_interface/util/UiUtils.cpp

@@ -197,8 +197,6 @@ UiUtils::PrintValueNodeGraph(BString& _output, StackFrame* frame,
 		return;
 	}
 
-	_output << " {\n";
-
 	if (node->CountChildren() == 1
 		&& node->GetType()->Kind() == TYPE_ADDRESS
 		&& node->ChildAt(0)->GetType()->Kind() == TYPE_COMPOUND) {
@@ -208,6 +206,9 @@ UiUtils::PrintValueNodeGraph(BString& _output, StackFrame* frame,
 		node = node->ChildAt(0)->Node();
 	}
 
+	if (node != NULL) {
+		_output << " {\n";
+
 		for (int32 i = 0; i < node->CountChildren(); i++) {
 			// don't dump compound nodes if our depth limit won't allow
 			// us to traverse into their children anyways, and the top
@@ -220,6 +221,7 @@ UiUtils::PrintValueNodeGraph(BString& _output, StackFrame* frame,
 		}
 		_output.Append('\t', indentLevel);
 		_output << "}\n";
+	}
 
 	return;
 }