const {Command} = require('./index.js');
const {wotblitz: {default_region}} = require('../../blitzbot.json');
const options = {
	argCount: 1,
	description: 'Update your personal default region.',
	signatures: ['@BOTNAME set-region [region]']
};
const command = new Command(setRegion, options, 'set-region');

module.exports = command;

async function setRegion(msg, region) {
	switch (region && region.toLowerCase()) {
	case 'asia':
	case 'a':
		region = 'asia';
		break;
	case 'eu':
	case 'e':
		region = 'eu';
		break;
	case 'ru':
	case 'r':
		region = 'ru';
		break;
	case 'na':
	case 'n':
		region = 'na';
		break;
	default:
		region = default_region;
		break;
	}

	const sent = await msg.reply('Region set to "' + region + '".');

	return {
		sentMsg: sent,
		master: true,
		updateFields: {
			region: region
		}
	};
}

const {Command} = require('./index.js');
const {wotblitz: {default_region}} = require('../../blitzbot.json');
const options = {
	argCount: 1,
	description: 'Update your personal default region.',
	signatures: ['@BOTNAME set-region [region]']
};
const command = new Command(setRegion, options, 'set-region');

module.exports = command;

function setRegion(msg, region) {
	switch (region && region.toLowerCase()) {
	case 'asia':
	case 'a':
		region = 'asia';
		break;
	case 'eu':
	case 'e':
		region = 'eu';
		break;
	case 'ru':
	case 'r':
		region = 'ru';
		break;
	case 'na':
	case 'n':
		region = 'na';
		break;
	default:
		region = default_region;
		break;
	}

	return msg.reply('Region set to "' + region + '".').then(sent => {
		return {
			sentMsg: sent,
			master: true,
			updateFields: {
				region: region
			}
		};
	});
}

--- 
+++ 
@@ -9,7 +9,7 @@
 
 module.exports = command;
 
-function setRegion(msg, region) {
+async function setRegion(msg, region) {
 	switch (region && region.toLowerCase()) {
 	case 'asia':
 	case 'a':
@@ -32,13 +32,13 @@
 		break;
 	}
 
-	return msg.reply('Region set to "' + region + '".').then(sent => {
-		return {
-			sentMsg: sent,
-			master: true,
-			updateFields: {
-				region: region
-			}
-		};
-	});
+	const sent = await msg.reply('Region set to "' + region + '".');
+
+	return {
+		sentMsg: sent,
+		master: true,
+		updateFields: {
+			region: region
+		}
+	};
 }
Use async patterns for set-region command.
