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-haste-map/build/lib/normalizePathSep.js

@@ -0,0 +1,37 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', {
+  value: true
+});
+exports.default = void 0;
+
+function _path() {
+  const data = _interopRequireDefault(require('path'));
+
+  _path = function _path() {
+    return data;
+  };
+
+  return data;
+}
+
+function _interopRequireDefault(obj) {
+  return obj && obj.__esModule ? obj : {default: obj};
+}
+
+/**
+ * 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.
+ */
+let normalizePathSep;
+
+if (_path().default.sep === '/') {
+  normalizePathSep = filePath => filePath;
+} else {
+  normalizePathSep = filePath => filePath.replace(/\//g, _path().default.sep);
+}
+
+var _default = normalizePathSep;
+exports.default = _default;