deal with empty remote

src/sync.ts

@@ -54,6 +54,7 @@ export const ensembleMixedStates = async (
 ) => {
   const results = {} as Record<string, FileOrFolderMixedState>;
 
+  if (remote !== undefined) {
     for (const entry of remote) {
       const backwardMapping = await getSyncMetaMappingByRemoteKeyS3(
         db,
@@ -89,6 +90,7 @@ export const ensembleMixedStates = async (
         results[key] = r;
       }
     }
+  }
 
   for (const entry of local) {
     let r = {} as FileOrFolderMixedState;