I've downloaded xip-archive of Xcode to my external drive and tried to unarchive it. Then I opened Xcode.app and got this error. Same error I've got on my internal drive.
My OS: macOS Hight Sierra 10.13.4
Xcode 9.3
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[MT] DVTPlugInLoading: Failed to load code for plug-in com.apple.dt.dbg.DebuggerLLDB (/Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin), error = Error Domain=NSCocoaErrorDomain Code=3587 "dlopen_preflight(/Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB): Library not loaded: @rpath/LLDB.framework/LLDB
Referenced from: /Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB
Reason: image not found" UserInfo={NSLocalizedFailureReason=The bundle is damaged or missing necessary resources., NSLocalizedRecoverySuggestion=Try reinstalling the bundle., NSFilePath=/Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB, NSDebugDescription=dlopen_preflight(/Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB): Library not loaded: @rpath/LLDB.framework/LLDB
Referenced from: /Volumes/Untitled/Xcode.app/
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[MT] DVTAssertions: Warning in /Library/Caches/com.apple.xbs/Sources/IDEFrameworks/IDEFrameworks-14154/IDEFoundation/Initialization/IDEInitialization.m:265
Details: Xcode failed its initial plug-in scan, error = Error Domain=DVTPlugInErrorDomain Code=2 "Loading a plug-in failed." UserInfo={DVTPlugInIdentifierErrorKey=com.apple.dt.dbg.DebuggerLLDB, DVTPlugInExecutablePathErrorKey=/Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB, NSLocalizedRecoverySuggestion=The plug-in or one of its prerequisite plug-ins may be missing or damaged and may need to be reinstalled., DVTPlugInDYLDErrorMessageErrorKey=dlopen(/Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB, 0): Library not loaded: @rpath/LLDB.framework/LLDB
Referenced from: /Volumes/Untitled/Xcode.app/Contents/PlugIns/DebuggerLLDB.ideplugin/Contents/MacOS/DebuggerLLDB
Reason: image not found, NSLocalizedDescription=Loading a plug-in failed.,