Update export.go (fix errcheck issue) (#28971)

server/.golangci.yml

@@ -83,7 +83,6 @@ issues:
         channels/app/bot_test.go|\
         channels/app/brand.go|\
         channels/app/config_test.go|\
-        channels/app/export.go|\
         channels/app/file.go|\
         channels/app/file_bench_test.go|\
         channels/app/file_test.go|\