Convert formatCustomFormatScore to Typescript

frontend/src/Utilities/Number/formatCustomFormatScore.ts

@@ -1,4 +1,7 @@
-function formatCustomFormatScore(input, customFormatsLength = 0) {
+function formatCustomFormatScore(
+  input?: number,
+  customFormatsLength = 0
+): string {
   const score = Number(input);
 
   if (score > 0) {
@@ -6,7 +9,7 @@ function formatCustomFormatScore(input, customFormatsLength = 0) {
   }
 
   if (score < 0) {
-    return score;
+    return `${score}`;
   }
 
   return customFormatsLength > 0 ? '+0' : '';