function ok(value, message = "Assertion failed.") {
	if (!value) {
		throw new Error(message);
	}
}
Throws an error if the input is not truthy.
@param {unknown} value The input that is checked for being truthy.
@param {string} message Message to throw if the input is not truthy.
@returns {void}
@throws {Error} When the condition is not truthy.