Underscores in `keyPrefix` cause `extractShortToken` to return the wrong segment

[zlalvani]

For example,

const { token } = await generateAPIKey({
  keyPrefix: "mycompany_token",
});

const shortToken = extractShortToken(token); // resolves to 'token'

This is caused by the implementation splitting the token on _ and always fetching the second element:

export const extractShortToken = (token: string) => token.split("_")?.[1]

One possible solution would be to adjust the logic to index backwards from the end:

export const extractShortToken = (token: string) => token.split("_").reverse()?.[1]

There could be a way to use template literal types to prevent the usage of _ in the prefix, but that would be challenging to implement if it was even possible.