Update NativeFsModule.swift

Co-authored-by: vadymv-mendix <138661748+vadymv-mendix@users.noreply.github.com>

Author: YogendraShelke

ios/Modules/NativeFsModule/NativeFsModule.swift

@@ -247,6 +247,7 @@ public class NativeFsModule: NSObject {
 
         do {
             try NativeFsModule.save(jsonData, filepath: filepath)
+            resolve(nil)
         } catch {
             reject(NativeFsModule.ERROR_SAVE_FAILED, NativeFsModule.formatError("Failed to write JSON"), error)
         }