Cache TypeScript support

[robert-nash]

I am using this library with nodecache as below.

import nodecache from "node-cache";

const flagsmith = new Flagsmith({
    environmentKey: "xxx",
    cache: new nodecache({
        stdTTL: 10,
        checkperiod: 10,
    }),
});

export default flagsmith;

I get the following type error on cache:

Type 'NodeCache' is not assignable to type 'FlagsmithCache'.
  The types returned by 'get(...)' are incompatible between these types.
    Type 'Promise<Flags> | undefined' is not assignable to type 'Promise<Flags>'.
      Type 'undefined' is not assignable to type 'Promise<Flags>'.

I wonder if this is a problem with the Flagsmith Types? It seems to make sense that the get method will return undefined when the key does not exist in the cache.

[kyle-ssg]

Fixed in 2.0.3