Basic error handling patterns

  signUp: publicProcedure
    .input(signUpSchema)
    .mutation(async ({ ctx, input }) => {
      try {
        // ... 

        // could throw on duplicate email.
        await ctx.db.insert(userTable).values(...);

        // ... 
      } catch (e) {
        if (isPgError(e) && e.constraint_name === "user_email_unique") {
          throw new TRPCError({
            code: "CONFLICT",
            message: "this email is already used",
          });
        }

        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: e instanceof Error ? e.message : "unhandled error",
        });
      }
    }),

  signUp: publicProcedure
    .input(signUpSchema)
    .use(async ({ctx, next})=>{
      const res = await next();

      // does not work since the instance of res.error is no longer PostgresError but TRPCError
      if(!res.ok && isPgError(res.error) && res.error.constraint_name === "user_email_unique") {
        throw new TRPCError({
          code: "CONFLICT",
          message: "this email is already used",
        });
      }

      throw new TRPCError({
        code: "INTERNAL_SERVER_ERROR",
        message: res.error instanceof Error ? res.error.message : "unhandled error",
      });
    })
    .mutation(async ({ ctx, input }) => {
        // ... 

        // could throw on duplicate email.
        await ctx.db.insert(userTable).values(...);

        // ... 
    }),