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/expectationResultFactory.d.ts

@@ -0,0 +1,17 @@
+/**
+ * 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.
+ */
+import { FailedAssertion } from '@jest/test-result';
+export declare type Options = {
+    matcherName: string;
+    passed: boolean;
+    actual?: any;
+    error?: any;
+    expected?: any;
+    message?: string | null;
+};
+export default function expectationResultFactory(options: Options, initError?: Error): FailedAssertion;
+//# sourceMappingURL=expectationResultFactory.d.ts.map