message: fix(collections): avoid fromNullable in mutable hash-set get
diff: @@ -57,7 +57,7 @@ export class HashMap<K, V> implements Iterable<readonly [K, V]> {
  while (c) {
  if (this.eqKey.equals(k, c.k)) {
  - return O.fromNullable(c.v)
  + return O.some(c.v)
  }
  c = c.next
  }
  