fixed spurious assert in FindControl() (backported from trunk)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@19447 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/tbarbase.cpp

@@ -212,14 +212,22 @@ wxControl *wxToolBarBase::FindControl( int id )
           node;
           node = node->GetNext() )
     {
-        wxControl *control = node->GetData()->GetControl();
-        
-        if (control)
+        const wxToolBarToolBase * const tool = node->GetData();
+        if ( tool->IsControl() )
         {
-            if (control->GetId() == id)
+            wxControl * const control = tool->GetControl();
+
+            if ( !control )
+            {
+                wxFAIL_MSG( _T("NULL control in toolbar?") );
+            }
+            else if ( control->GetId() == id )
+            {
+                // found
                 return control;
             }
         }
+    }
 
    return NULL;
 }