Describe the bug
In the method validateInvoice there is a typo error in the line 343, the file is validation.ts, but I'm thinking that method is not used anywhere.

In other case the line should be:

if (!("MIN_PAYMENT_AMT" in process.env)) throw Error("MIN_PAYMENT_AMT not found, please check .env file");

instead of:

if (!("MAIN_PAYMENT_AMT" in process.env)) throw Error("MIN_PAYMENT_AMT not found, please check .env file");

And there is some console.debug that weren't removed in the lines 392-394, and I'm not totally sure if the line 391 is doing the right validation, the result of a new Date is an Object