xdr union switch on number causes invalid typescript class generation

[sreuland]

Describe the bug
ts generated code for an xdr union switch based on number, the resulting ts class generates an invalid x(arm value): union static factory method for any switched values beyond 0, the method name is just the number x, which is invalid js syntax.

What version are you on?
1.3.0

To Reproduce
https://github.com/stellar/js-stellar-base/blob/soroban/types/next.d.ts#L11589 has generated ts code for TransactionExt class with static 1(value: SorobanTransactionData): TransactionExt; which is not a callable method in js.

https://github.com/stellar/js-stellar-base/blob/soroban/src/generated/next_generated.js#L5368 has the generated js code defining the mapping for xdr union and switch values.

the source xdr defining this union with numeric switch values - https://github.com/stellar/stellar-xdr/blob/next/Stellar-transaction.x#L869, excerpt here:

struct Transaction
{
   ...
    union switch (int v)
    {
    case 0:
        void;
    case 1:
        SorobanTransactionData sorobanData;
    }
    ext;
};

to reproduce the behavior locally, use js-stellar-base as it uses dts-xdr and compiles this xdr def:

1. checkout github.com/stellar/js-stellar-base
2. run make reset-xdr from checked out directory

in either case, looking at the resulting js-stellar-base/types/next.d.ts, will see TransactionExt with the incorrectly named factory method.

Expected behavior
a static ts method declaration for the armed switch name such as TransactionExt.sorobanData(value: SorobanTransactionData): TransactionExt

Additional context
What is the expected way to use the generated code to create an instance of one of these unions given you have an arm value, it seems like these static methods named after the switch value are intended for that, otherwise, the default constructor on the ts class doesn't work, I tried that first, which does create an object, but when using the class instance method provided to set the arm value sorobanData(sorobanTransactionData) it doesn't appear to do anything as the value() return undefined afterwards.

one potential work around is to create instance from the static factory method fromXDR(string) and use a hardcoded serialized xdr string representing an empty instance if possible.