function checkFlags(requireFlag, flags) {
	let missingFlag;

	if (requireFlag === "v") {
		missingFlag = !flags.includes("v");
	} else if (requireFlag === "u") {
		missingFlag = !flags.includes("u");
	} else {
		missingFlag = !flags.includes("u") && !flags.includes("v");
	}

	return missingFlag;
}
Checks whether the flag configuration should be treated as a missing flag.
@param {"u"|"v"|undefined} requireFlag A particular flag to require
@param {string} flags The regex flags
@returns {boolean} Whether the flag configuration results in a missing flag.