Fix deprecation error in the route:list command (#42704)

Author: bonzai

src/Illuminate/Foundation/Console/RouteListCommand.php

@@ -400,7 +400,7 @@ protected function forCli($routes)
                 $spaces,
                 preg_replace('#({[^}]+})#', '<fg=yellow>$1</>', $uri),
                 $dots,
-                str_replace('   ', ' › ', $action),
+                str_replace('   ', ' › ', $action ?? ''),
             ), $this->output->isVerbose() && ! empty($middleware) ? "<fg=#6C7280>$middleware</>" : null];
         })
             ->flatten()