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-runtime/build/cli/args.d.ts

@@ -0,0 +1,10 @@
+/**
+ * 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 { Options } from 'yargs';
+export declare const usage = "Usage: $0 [--config=<pathToConfigFile>] <file>";
+export declare const options: Record<'cache' | 'config' | 'debug' | 'version' | 'watchman', Options>;
+//# sourceMappingURL=args.d.ts.map