message: Remove null primitive test
  The TypeScript type system will automatically disallow null primitives. It is arguably desirable to also have this enforcement at runtime, but doing this in a consistent way is a bigger project that we've already decided to defer for now.
diff: @@ -39,20 +39,6 @@ describe('primitive set test', function() {
  fail('An exception should be thrown.');
  });
  - it('add primitive null primitive', function() {
  - const primitive = null;
  - const key = createKey();
  - const primitiveSet = new PrimitiveSet.PrimitiveSet(Aead);
  -
  - try {
  - primitiveSet.addPrimitive(primitive, key);
  - } catch (e) {
  - expect(e.toString()).toBe(ExceptionText.addingNullPrimitive());
  - return;
  - }
  - fail('An exception should be thrown.');
  - });
  -
  it('add primitive multiple times should work', function() {
  const key = createKey();
  const primitiveSet = new PrimitiveSet.PrimitiveSet(Aead);
  