make eslint happy

also add some types to `chiptune2.ts`

packages/frontend/src/scripts/nyaize.ts

@@ -9,9 +9,9 @@ const koRegex3 = /(야(?=\?))|(야$)|(야(?= ))/gm;
 
 function ifAfter(prefix, fn) {
 	const preLen = prefix.length;
-	const regex = new RegExp(prefix,'i');
-	return (x,pos,string) => {
-		return pos > 0 && string.substring(pos-preLen,pos).match(regex) ? fn(x) : x;
+	const regex = new RegExp(prefix, 'i');
+	return (x, pos, string) => {
+		return pos > 0 && string.substring(pos - preLen, pos).match(regex) ? fn(x) : x;
 	};
 }
 
@@ -25,7 +25,7 @@ export function nyaize(text: string): string {
 		.replace(/one/gi, ifAfter('every', x => x === 'ONE' ? 'NYAN' : 'nyan'))
 		// ko-KR
 		.replace(koRegex1, match => String.fromCharCode(
-			match.charCodeAt(0)! + '냐'.charCodeAt(0) - '나'.charCodeAt(0),
+			match.charCodeAt(0) + '냐'.charCodeAt(0) - '나'.charCodeAt(0),
 		))
 		.replace(koRegex2, '다냥')
 		.replace(koRegex3, '냥');