Fix: Create BigNumber with NaN value in Dish.valid

[sivachandran]

Description
The constructor expects the default value but we are not passing it. So it was throwing undefined error. Now passing NaN as default value.

Existing Issue
#2567

Screenshots

Console error

Uncaught Error: [BigNumber Error] BigNumber, string, number, or BigInt expected: undefined
    P https://gchq.github.io/CyberChef/assets/main.js:2
    value https://gchq.github.io/CyberChef/assets/main.js:2
    value https://gchq.github.io/CyberChef/assets/main.js:2
    e https://gchq.github.io/CyberChef/assets/main.js:2
    value https://gchq.github.io/CyberChef/assets/main.js:2
    value https://gchq.github.io/CyberChef/assets/main.js:2
    value https://gchq.github.io/CyberChef/assets/main.js:2

AI disclosure
Didn't use AI.

Test Coverage
Added a test.

[CLAassistant]

All committers have signed the CLA.

[GCHQDeveloper581]

better still,

this.value = new BigNumber({ s: this.value.s, e: this.value.e, c: this.value.c, _isBigNumber: true});

See

• https://mikemcl.github.io/bignumber.js/#instance-properties
• https://mikemcl.github.io/bignumber.js/#bignumber:~:text=In-,advanced,-usage%2C%20a%20BigNumber