The decoded string is wrong when vatRegistrationNumber length is 15

[dev-sahar]

Issue description

When I increase the vatRegistrationNumber to 15 characters/numbers (which is the length of the vat registration number for my KSA company) the decoded string gets missed up.

Steps to reproduce the issue

1. use this as a sample

    const invoice = new Invoice({
       sellerName: 'شركة تجريبية',
       vatRegistrationNumber: '123456789135785',
       invoiceTimestamp: '2021-02-21T11:20:27.983Z',
       invoiceTotal: '2785.8',
       invoiceVatTotal: '361.8',
     })
   
     invoice.toBase64()

2. then take the generated base64 string to https://www.base64decode.org/
3. decode and check the results

What's the expected result?

a readable string similar to this

شركة تجريبية
1234567891357852021-02-21T11:20:27.983Z2785.8361.8

What's the actual result?

[ihadabs]

Hi @dev-sahar,

I'm gonna look at it tomorrow, if you can fix the issue, please create a pull request 🙌.

[ihadabs]

@dev-sahar

I how did you asume that the result is invalid? Just checked the output with the ZATCA SDK for the values you provided and it was decoded correctly.

If we're missing somthing here, please, elaborate more.