I think i found an TRPC BUG

I am using TRPC With Fastify and bun (node.js alternative) if you try to call any .mutation route the application crashes. Router example:
export const appRouter = router({
ping: publicProcedure.mutation(() => {
console.log("pong");
return { message: "pong" };
}),
});
export const appRouter = router({
ping: publicProcedure.mutation(() => {
console.log("pong");
return { message: "pong" };
}),
});
error is screenshot I also edited the package to console log resource.runin.... and it came back as undefined, this does not happen when using .query