function assertValidFix(fix) {
	if (fix) {
		assert(
			fix.range &&
				typeof fix.range[0] === "number" &&
				typeof fix.range[1] === "number",
			`Fix has invalid range: ${JSON.stringify(fix, null, 2)}`,
		);
	}
}
Check that a fix has a valid range.
@param {Fix|null} fix The fix to validate.
@returns {void}