JS-port of MySQL (My Sector, Queue, List?) TinyInt

TinyInt.js

class TinyInt {
  constructor(N = 0, sign) {
    this.n = N;
    switch (sign) {
      case "unsigned":
        if (N < 256 && N >= 0 && N % 1 == 0) {
          return this.n;
        } else if (N % 1 == 0) {
          return new Error(
            "SOLVE ERROR_UNSIGNED_TINYINT: Number OutOfRange (0/255)"
          );
        } else if (N < 256 && N >= 0) {
          return new Error(
            "SOLVE ERROR_UNSIGNED_TINYINT: Number Is A Float (N%1 != 0)"
          );
        }
      case "signed":
        if (N > -129 && N <= 127 && N % 1 == 0) {
          return this.n;
        } else if (N % 1 == 0) {
          return new Error(
            "SOLVE ERROR_SIGNED_TINYINT: Number OutOfRange (-129/127)"
          );
        } else if (N < 256 && N >= 0) {
          return new Error(
            "SOLVE ERROR_SIGNED_TINYINT: Number Is A Float (N%1 != 0)"
          );
        }
      default:
        break;
    }
  }

  toBigInt() {
    return BigInt(this.n);
  }
  toStr() {
    return this.n.toString(36);
  }
  ExpForm() {
    return this.n.toExponential(21);
  }
  Precision() {
    return this.n.toPrecision(21);
  }
  FixedForm() {
    return this.n.toFixed(20);
  }
  Extend(extendition) {
    if (extendition <= 0) {
      return 0;
    } else {
      return this.n * extendition;
    }
  }
}