Nothing displaying on preview , Save button not working and there is Errors messages Xcode 9.2

[X901]

Hi ,
I just tried the application with different JSON files and I did choose different format / Language

nothing working !!

and I got these errors

2018-02-21 19:05:43.425771+0300 JSONExport[15764:1328438] Unknown Window class (null) in Interface Builder file,
	 creating generic Window instead
objc[15764]: Class FIFinderSyncExtensionHost is implemented in both /System/Library/PrivateFrameworks/FinderKit.framework/Versions/A/FinderKit (0x7fff85b54b68) and /System/Library/PrivateFrameworks/FileProvider.framework/OverrideBundles/FinderSyncCollaborationFileProviderOverride.bundle/Contents/MacOS/FinderSyncCollaborationFileProviderOverride (0x10d641cd8). One of the two will be used. Which one is undefined.
2018-02-21 19:06:38.138051+0300 JSONExport[15764:1328438] MessageTracer: Falling back to default whitelist
2018-02-21 19:06:39.253854+0300 JSONExport[15764:1331396] errors encountered while discovering extensions: Error Domain=PlugInKit Code=13 "query cancelled" UserInfo={NSLocalizedDescription=query cancelled}

[X901]

I noticed if the JSON File is very big file like there is 100k entire it won't work
it will tell me Valid JSON
but won't preview or let me Save it and it will get me these errors