[vm/compiler] Check for errors when loading test scripts.

Change-Id: Iccec96b86ac9bca5bb53e8dc0fb2aa30fde24fd3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/101261
Auto-Submit: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
diff --git a/runtime/vm/compiler/backend/il_test_helper.cc b/runtime/vm/compiler/backend/il_test_helper.cc
index 4315c29..ddcb033 100644
--- a/runtime/vm/compiler/backend/il_test_helper.cc
+++ b/runtime/vm/compiler/backend/il_test_helper.cc
@@ -28,6 +28,7 @@
   {
     TransitionVMToNative transition(Thread::Current());
     api_lib = TestCase::LoadTestScript(script, resolver, lib_uri);
+    EXPECT_VALID(api_lib);
   }
   auto& lib = Library::Handle();
   lib ^= Api::UnwrapHandle(api_lib);