function calculateStatsPerFile(messages) {
	const stat = {
		errorCount: 0,
		fatalErrorCount: 0,
		warningCount: 0,
		fixableErrorCount: 0,
		fixableWarningCount: 0,
	};

	for (let i = 0; i < messages.length; i++) {
		const message = messages[i];

		if (message.fatal || message.severity === 2) {
			stat.errorCount++;
			if (message.fatal) {
				stat.fatalErrorCount++;
			}
			if (message.fix) {
				stat.fixableErrorCount++;
			}
		} else {
			stat.warningCount++;
			if (message.fix) {
				stat.fixableWarningCount++;
			}
		}
	}
	return stat;
}
It will calculate the error and warning count for collection of messages per file
@param {LintMessage[]} messages Collection of messages
@returns {Object} Contains the stats
@private