Throw error with seth 4byte if no matching signatures

[transmissions11]

right now if you search up a 4byte sig with no matches the command just succeeds but returns nothing:

❯ seth 4byte 0xd0a164fb

can see why with verbose:

❯ seth 4byte 0xd0a164fb -v
{
  "count": 0,
  "next": null,
  "previous": null,
  "results": []
}

it should show an error message and exit with an error code like 1 if no results are found instead