feat: disabled the default check for the upstream encoder

[khi195]

this is a PR for the following issue
#643

for the upstream encoder, this PR has the ability to disable the check for default enums, because for proto2 we may not have a default enum, so will have to disable the default behaviour.

[stephenh]

Hey @khi195 ; thanks for the PR! Instead of adding more options, I think we should try and solve this by being smarter at handling "there is no enum with value === 0".

I.e. this line is calling notDefaultCheck, which inside of that method has some code that looks like:

      const zerothValue = enumProto.value.find((v) => v.number === 0) || enumProto.value[0];
      if (options.stringEnums) {
        const enumType = messageToTypeName(ctx, field.typeName);
        return code`${maybeNotUndefinedAnd} ${place} !== ${enumType}.${zerothValue.name}`;
      } else {
        return code`${maybeNotUndefinedAnd} ${place} !== ${zerothValue.number}`;
      }

Note the || enumProto.value[0]. That is the line that is tripping up your code, b/c it means ts-proto is treating the "the enum value 1" as the default, which it just shouldn't do.

Can you try removing that || enumProto.value[0] and instead doing something like:

      const zerothValue = enumProto.value.find((v) => v.number === 0);
      if (!zerothValue) {
        return undefined;
      } else if (options.stringEnums) {
        const enumType = messageToTypeName(ctx, field.typeName);
        return code`${maybeNotUndefinedAnd} ${place} !== ${enumType}.${zerothValue.name}`;
      } else {
        return code`${maybeNotUndefinedAnd} ${place} !== ${zerothValue.number}`;
      }

And then here in the generateEncode method, you could do:

const maybeDefaultCheck = notDefaultCheck(ctx, field, messageDesc.options, `message.${fieldName}`);

And if maybeDefaultCheck is undefined, then leave the if statement out, just like you're currently doing by looking at the new disableDefaultCheck options.

I'm pretty sure that should work.