Added checks to make sure the specified track exists

Added precondition checks to validate input files and paths to return more informative error messages as per #2

node_modules/jest-jasmine2/build/jasmineAsyncInstall.d.ts

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+/**
+ * This module adds ability to test async promise code with jasmine by
+ * returning a promise from `it/test` and `before/afterEach/All` blocks.
+ */
+import { Global, Config } from '@jest/types';
+export default function jasmineAsyncInstall(globalConfig: Config.GlobalConfig, global: Global.Global): void;
+//# sourceMappingURL=jasmineAsyncInstall.d.ts.map