message: fixing type error
  introduced while testing some things out
diff: @@ -20,8 +20,8 @@ describe("Signal", () => {
  });
  it("can be created with an options object", () => {
  - const signal = new Signal<Time>({
  - units: "time",
  + const signal = new Signal({
  + units: "positive",
  value: 0.2,
  });
  expect(signal.value).to.be.closeTo(0.2, 0.001);
  