I'm developing a Safari App Extension. Previously it worked fine. When I run the project in Xcode, and enable Allow Unsigned Extensions in Safari, I can see my extension in Safari Preferences -> Extensions page.After I merged code with one of my team member, suddenly the Extension cannot get installed.I have tried:Clean the build folder in Xcode, and run again. But no luck.Restart Xcode doesn't help either.Use command pluginkit -mAvvv -p com.apple.Safari.extension to check installed Safari extensions list. My extension is not in the list.There are some errors in Xcode output, but I can't link them with the issue I'm facing:objc[59117]: Class AMSupportURLConnectionDelegate is implemented in both /System/Library/PrivateFrameworks/EmbeddedOSInstall.framework/Versions/A/EmbeddedOSInstall (0x7fff9a2aa748) and /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice (0x1063e8600). One of the two will be used. Which one is undefined.objc[59117]: Class AMSupportURLSession is implemented in both /System/Library/PrivateFrameworks/OSPersonalization.framework/Versions/A/OSPersonalization (0x7fff9b5d49f0) and /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice (0x1063e8650). One of the two will be used. Which one is undefined.2018-12-13 17:28:16.710744+0800 Safari[59117:1304953] Could not connect action, target class SecurityPreferences does not respond to -toggleJavaScriptCanOpenWindows:2018-12-13 17:28:16.833463+0800 Safari[59117:1304953] AssertMacros: 0 (value = 0x0), file: /BuildRoot/Library/Caches/com.apple.xbs/Sources/BiometricKit/BiometricKit-75.71.1/BiometricKit/BiometricKitXPCClient.m, line: 752018-12-13 17:28:16.833544+0800 Safari[59117:1304953] AssertMacros: 0 (value = 0x0), file: /BuildRoot/Library/Caches/com.apple.xbs/Sources/BiometricKit/BiometricKit-75.71.1/BiometricKit/BiometricKitXPCClient.m, line: 3962018-12-13 17:28:16.833650+0800 Safari[59117:1304953] [Framework-Internal-Legacy] AssertMacros: _xpcClient (value = 0x0), file: /BuildRoot/Library/Caches/com.apple.xbs/Sources/BiometricKit/BiometricKit-75.71.1/BiometricKit/BiometricKit.m, line: 1372018-12-13 17:28:17.300775+0800 Safari[59117:1304985] [RemotePlistController] The downloaded plist could not be loaded: Error Domain=NSCocoaErrorDomain Code=260 "The file couldn’t be opened because it doesn’t exist."2018-12-13 17:28:17.841024+0800 Safari[59117:1304996] NSURLConnection finished with error - code -11002018-12-13 17:28:18.008953+0800 Safari[59117:1305029] [CrowdsourcedAutoFill] Unable to read cloud AutoFill correction sets, error: Error Domain=NSCocoaErrorDomain Code=260 "The file couldn’t be opened because it doesn’t exist."2018-12-13 17:28:18.049658+0800 Safari[59117:1305028] [CloudBookmarks] Error fetching remote migration state: Error Domain=com.apple.SafariBookmarksSync.CloudBookmarksErrorDomain Code=0 "(null)"2018-12-13 17:28:18.521444+0800 Safari[59117:1305032] NSURLConnection finished with error - code -11002018-12-13 17:28:18.544894+0800 Safari[59117:1305188] [RemotePlistController] The downloaded plist could not be loaded: Error Domain=NSCocoaErrorDomain Code=260 "The file couldn’t be opened because it doesn’t exist."2018-12-13 17:28:18.659265+0800 Safari[59117:1305029] Calling IOPPFGetProperty simulator_utility_clamp!2018-12-13 17:28:18.957830+0800 Safari[59117:1304953] [WebKit2Callbacks] Page (pid: 59135) did become unresponsive2018-12-13 17:28:19.684984+0800 Safari[59117:1304953] [WebKit2Callbacks] Page (pid: 59135) did become responsive2018-12-13 17:28:19.790156+0800 Safari[59117:1304997] [RemotePlistController] The downloaded plist could not be loaded: Error Domain=NSCocoaErrorDomain Code=260 "The file couldn’t be opened because it doesn’t exist."2018-12-14 10:49:13.324838+0800 Safari[59117:1324361] [CrowdsourcedAutoFill] Unable to read cloud AutoFill correction sets, error: Error Domain=NSCocoaErrorDomain Code=260 "The file couldn’t be opened because it doesn’t exist."2018-12-14 10:49:13.415684+0800 Safari[59117:1326314] [CrowdsourcedAutoFill] Unable to read cloud AutoFill correction sets, error: Error Domain=NSCocoaErrorDomain Code=260 "The file couldn’t be opened because it doesn’t exist."Now I'm running out of options. It lacks official documentation in Apple Developer site.Is there regular steps to troubleshoot this kind of issue? Is there any kind of system logs which can help me address the error? Any suggestion is appreciated.