Resolve #2631 (#2632)

src/client/app/common/scripts/gcd.ts

-const gcd = (a, b) => !b ? a : gcd(b, a % b);
-export default gcd;

src/client/app/mobile/views/components/drive.file-detail.vue

@@ -67,7 +67,7 @@
 import Vue from 'vue';
 import * as EXIF from 'exif-js';
 import * as hljs from 'highlight.js';
-import gcd from '../../../common/scripts/gcd';
+import { gcd } from '../../../../../prelude/math';
 
 export default Vue.extend({
 	props: ['file'],

src/prelude/math.ts

+export function gcd(a: number, b: number): number {
+	return b === 0 ? a : gcd(b, a % b);
+}