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/core/build/TestNamePatternPrompt.d.ts

@@ -0,0 +1,18 @@
+/**
+ * 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.
+ */
+/// <reference types="node" />
+import { PatternPrompt, Prompt, ScrollOptions } from 'jest-watcher';
+import { TestResult } from '@jest/test-result';
+export default class TestNamePatternPrompt extends PatternPrompt {
+    _cachedTestResults: Array<TestResult>;
+    constructor(pipe: NodeJS.WritableStream, prompt: Prompt);
+    _onChange(pattern: string, options: ScrollOptions): void;
+    _printPrompt(pattern: string): void;
+    _getMatchedTests(pattern: string): string[];
+    updateCachedTestResults(testResults?: Array<TestResult>): void;
+}
+//# sourceMappingURL=TestNamePatternPrompt.d.ts.map