type Instruction = InstructionType1 | InstructionType2 | ...;
type InstructionType1 = {
  type: "InstructionType1";
  selector: string;
  ...
}

// This way we can do the following in the future:

const handleInstruction = (instruction: Instruction): void => { // for example
  switch (instruction.type) {
   // ts error if the type is not in the tagged union
    case "InstructionType1": f();
      break;
    case "InstructionType2":  g();
      break;
    default: {
      // we get a type error if we aren't handling every case
      const exhaustivenessCheck: never = ""
    }
  }
};