Incorrect TypeScript Typings for `fail_existing` in customers.create (should allow '0' | '1' strings)

Steps to reproduce the behavior

1. Create a new Node.js project using TypeScript.

2. Install the Razorpay package by running: npm install razorpay@2.9.6.

3. Set up the Razorpay client with your API keys, then attempt to create a new customer using the following code:

await razorpay.customers.create({
  contact: '....',
  email: '....',
  fail_existing: 0
});

see the video for more clarity onedrive_link
If you run this code the first time, it should work. If you try again, you may receive an error indicating that the customer already exists in your merchant account.

Expected behavior

The type definition should be:

fail_existing?: '0' | '1' | undefined;

so that valid strings are allowed.

Actual behavior

It currently allows:

fail_existing?: boolean | 1 | 0 | undefined;

which does not match actual API behavior.

Code snippets

Node version

Node v22.20.0

Library version

razorpay v2.9.6

Additional Information

No response

Start at the TypeScript definition used by customers.create and compare the fail_existing type with the expected API values described in the issue. Done means the customer creation input accepts the documented string values and the package's TypeScript checks pass.