fix(i18n): fix that unable to delete page with SINGLE_FILE i18n structure (#6218)

fixes that getFilePaths returns same path twice when i18n structure is SINGLE_FILE

Author: ManojBahuguna

packages/netlify-cms-core/src/lib/__tests__/i18n.spec.js

@@ -181,6 +181,17 @@ describe('i18n', () => {
         ),
       ).toEqual(['src/content/en/index.md', 'src/content/de/index.md']);
     });
+
+    it('should return array with single path when structure is I18N_STRUCTURE.SINGLE_FILE', () => {
+      expect(
+        i18n.getFilePaths(
+          fromJS({
+            i18n: { structure: i18n.I18N_STRUCTURE.SINGLE_FILE, locales: ['en', 'de'] },
+          }),
+          ...args,
+        ),
+      ).toEqual(['src/content/index.md']);
+    });
   });
 
   describe('normalizeFilePath', () => {

packages/netlify-cms-core/src/lib/i18n.ts

@@ -114,6 +114,11 @@ export function getFilePaths(
   slug: string,
 ) {
   const { structure, locales } = getI18nInfo(collection) as I18nInfo;
+
+  if (structure === I18N_STRUCTURE.SINGLE_FILE) {
+    return [path];
+  }
+
   const paths = locales.map(locale =>
     getFilePath(structure as I18N_STRUCTURE, extension, path, slug, locale),
   );