Don't assume footer is present in _ConsoleOutputState builder. (#9342)

---------

Co-authored-by: Nate Biggs <[email protected]>

Author: biggs0125

packages/devtools_app/lib/src/shared/console/console.dart

@@ -209,10 +209,11 @@ class _ConsoleOutputState extends State<_ConsoleOutput>
                 ),
               ),
               // consider constraining a max height.
-              Padding(
-                padding: const EdgeInsets.only(top: denseSpacing),
-                child: widget.footer!,
-              ),
+              if (widget.footer != null)
+                Padding(
+                  padding: const EdgeInsets.only(top: denseSpacing),
+                  child: widget.footer,
+                ),
             ],
           ),
         ),