Function length

test/32.database.function.js:38–38

	});
	it('should throw an exception if function.length is invalid', function () {
		const length = x => Object.defineProperty(() => {}, 'length', { value: x });
		expect(() => this.db.function('a', length(undefined))).to.throw(TypeError);
		expect(() => this.db.function('b', length(null))).to.throw(TypeError);
		expect(() => this.db.function('c', length('2'))).to.throw(TypeError);