Handle invalid serialization when using transformers

[jludwiggreenaction]

When using a transformer (such as superjson as shown in the documenation), it is possible the transformation will fail.

I've tested this by using the fastify TRPC plugin and superjson transformer. Sending invalid input causes the server to always throw 500, since the parse error is thrown before ever making it to the procedures.

Right now I'm thinking that you have to make your own wrapper around the transformer's functions that fulfills the transformer interface:

// before
transformer: superjson,

// after
transformer: {
  output: superjson,
  input: {
    serialize: superjson.serialize,
    deserialize(data) {
      try {
        return superjson.deserialize(data);
      } catch (err) {
        throw new TRPCError({
          code: 'PARSE_ERROR',
          cause: err,
          message: 'input was unable to be transformed',
        });
      }
    },
  },
},

Thanks for any input you may have.