Fix model:prune error with non-class php files (#48708)

Author: zlodes

src/Illuminate/Database/Console/PruneCommand.php

@@ -138,10 +138,10 @@ protected function models()
                 return $models->reject(function ($model) use ($except) {
                     return in_array($model, $except);
                 });
-            })->filter(function ($model) {
-                return $this->isPrunable($model);
             })->filter(function ($model) {
                 return class_exists($model);
+            })->filter(function ($model) {
+                return $this->isPrunable($model);
             })->values();
     }