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/persistence/file.d.ts

@@ -0,0 +1,9 @@
+import { InternalHasteMap, Persistence } from '../types';
+declare class FilePersistence implements Persistence {
+    write(cachePath: string, internalHasteMap: InternalHasteMap): void;
+    read(cachePath: string): InternalHasteMap;
+    getType(): string;
+}
+declare const _default: FilePersistence;
+export default _default;
+//# sourceMappingURL=file.d.ts.map