Fix use-after-free on error during module evaluation

E.g. if during evaluation of module A, we start loading module B and
an error occurs. This results in a call to js_free_modules() with
JS_FREE_MODULE_NOT_EVALUATED, and since module A isn't yet evaluated,
it gets freed prematurely.

To solve this we improve js_free_modules() to ensure `eval_mark` is not
set. Once js_evaluate_module() returns for module A, it will notice that
an exception occurred and call js_free_modules() with
JS_FREE_MODULE_NOT_EVALUATED. Since `eval_mark` has been cleared by then,
module A gets cleaned up as well.

Co-authored-by: Ole André Vadla Ravnås <[email protected]>

quickjs.c

@@ -2225,7 +2225,8 @@ static void js_free_modules(JSContext *ctx, JSFreeModuleEnum flag)
         JSModuleDef *m = list_entry(el, JSModuleDef, link);
         if (flag == JS_FREE_MODULE_ALL ||
             (flag == JS_FREE_MODULE_NOT_RESOLVED && !m->resolved) ||
-            (flag == JS_FREE_MODULE_NOT_EVALUATED && !m->evaluated)) {
+            (flag == JS_FREE_MODULE_NOT_EVALUATED && !m->evaluated
+                && !m->eval_mark)) {
             js_free_module_def(ctx, m);
         }
     }
@@ -28009,6 +28010,7 @@ static JSValue js_evaluate_module(JSContext *ctx, JSModuleDef *m)
             ret_val = js_evaluate_module(ctx, m1);
             if (JS_IsException(ret_val)) {
                 m->eval_mark = FALSE;
+                js_free_modules(ctx, JS_FREE_MODULE_NOT_EVALUATED);
                 goto clean;
             }
             if (!JS_IsUndefined(ret_val)) {