fix: more imports

packages/core/src/math/isNumber.ts

@@ -1,3 +1,3 @@
-export default function isNumber(value: any) {
+export function isNumber(value: any) {
   return typeof value === 'number' && isFinite(value);
 }

packages/core/src/math/numberToRomanNumeral.ts

@@ -19,7 +19,7 @@ const ROMAN = {
 };
 const ROMAN_KEYS = Object.keys(ROMAN) as (keyof typeof ROMAN)[];
 
-export default function numberToRomanNumeral(value: number) {
+export function numberToRomanNumeral(value: number) {
   let string = '';
 
   ROMAN_KEYS.forEach((index) => {