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/map-age-cleaner/dist/index.d.ts

@@ -0,0 +1,20 @@
+interface Entry {
+    [key: string]: any;
+}
+interface MaxAgeEntry extends Entry {
+    maxAge: number;
+}
+/**
+ * Automatically cleanup the items in the provided `map`. The property of the expiration timestamp should be named `maxAge`.
+ *
+ * @param map - Map instance which should be cleaned up.
+ */
+export default function mapAgeCleaner<K = any, V extends MaxAgeEntry = MaxAgeEntry>(map: Map<K, V>): any;
+/**
+ * Automatically cleanup the items in the provided `map`.
+ *
+ * @param map - Map instance which should be cleaned up.
+ * @param property - Name of the property which olds the expiry timestamp.
+ */
+export default function mapAgeCleaner<K = any, V = Entry>(map: Map<K, V>, property: string): any;
+export {};