Xcode 10 playground input "{" crash

Process:               Xcode [47032]
Path:                  /Applications/Xcode.app/Contents/MacOS/Xcode
Identifier:            com.apple.dt.Xcode
Version:               10.0 (14320.25)
Build Info:            IDEFrameworks_Fall2018-14320025000000000~2
App Item ID:           497799835
App External ID:       828536089
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           Xcode [47032]
User ID:               501


Date/Time:             2018-10-14 17:22:24.795 +0800
OS Version:            Mac OS X 10.14 (18A391)
Report Version:        12
Anonymous UUID:        242B4C52-B558-5912-728F-56E4401779C6


Sleep/Wake UUID:       AF92574B-36C8-4F39-B2E6-2998B5518D13


Time Awake Since Boot: 460000 seconds
Time Since Wake:       3100 seconds


System Integrity Protection: enabled


Crashed Thread:        0  Dispatch queue: com.apple.main-thread


Exception Type:        EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes:       0x0000000000000001, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY


Termination Signal:    Illegal instruction: 4
Termination Reason:    Namespace SIGNAL, Code 0x4
Terminating Process:   exc handler [47032]


Application Specific Information:
ProductBuildVersion: 10A255
Crashing on exception: *** -[__NSCFString rangeOfCharacterFromSet:options:range:]: Range {0, 4766} out of bounds; string length 4250


Application Specific Backtrace 1:
0   CoreFoundation                      0x00007fff433e043d __exceptionPreprocess + 256
1   DVTFoundation                       0x0000000100c8af71 DVTFailureHintExceptionPreprocessor + 274
2   libobjc.A.dylib                     0x00007fff6f2ed720 objc_exception_throw + 48
3   CoreFoundation                      0x00007fff433e026f +[NSException raise:format:] + 201
4   Foundation                          0x00007fff456c12e1 -[NSString rangeOfCharacterFromSet:options:range:] + 171
5   IDEPegasusPlaygroundEditor          0x000000011c268079 $S26IDEPegasusPlaygroundEditor0B8DocumentC25previousCharacterPosition33_304ABAEE8C8C56C228038B23F9F4185FLL5inSet04fromG006SourceC00rcG0VSg10Foundation0fP0V_AJtF + 233
6   IDEPegasusPlaygroundEditor          0x000000011c2683b5 $S26IDEPegasusPlaygroundEditor0B8DocumentC33rangeOfEnclosingContextAtPositiony06SourceC00kC5RangeVSgAE0kcJ0VF + 645
7   IDEPegasusPlaygroundEditor          0x000000011c269fc1 $S26IDEPegasusPlaygroundEditor0B8DocumentC23alternateExecutableLine03forG014recurseCounterSiSgSi_SitF + 289
8   IDEPegasusPlaygroundEditor          0x000000011c28f66d $S26IDEPegasusPlaygroundEditor25ExecutableRegionAccessory33_34E08EDDF25C012D00A480F8D84AF2A8LLC24buttonLineWithMouseHoverSivg + 797
9   IDEPegasusPlaygroundEditor          0x000000011c28ef46 $S26IDEPegasusPlaygroundEditor25ExecutableRegionAccessory33_34E08EDDF25C012D00A480F8D84AF2A8LLC8barRangeSnySiGvg + 54
10  IDEPegasusPlaygroundEditor          0x000000011c28f07e $S26IDEPegasusPlaygroundEditor25ExecutableRegionAccessory33_34E08EDDF25C012D00A480F8D84AF2A8LLC18invalidateBarRangeyyF + 94
11  IDEPegasusPlaygroundEditor          0x000000011c290263 $S26IDEPegasusPlaygroundEditor25ExecutableRegionAccessory33_34E08EDDF25C012D00A480F8D84AF2A8LLC15updateBarRangesyyF + 51
12  IDEPegasusPlaygroundEditor          0x000000011c290ab8 $S26IDEPegasusPlaygroundEditor25ExecutableRegionAccessory33_34E08EDDF25C012D00A480F8D84AF2A8LLC13updateDisplay7animateySb_tF + 120
13  IDEPegasusPlaygroundEditor          0x000000011c292ca5 $S26IDEPegasusPlaygroundEditor25ExecutableRegionAccessory33_34E08EDDF25C012D00A480F8D84AF2A8LLC06SourceC019LayoutVisualizationAaeFP04willQ13InContentViewyyAE0pcuV0CFTW + 37
14  SourceEditor                        0x0000000118284c65 $S12SourceEditor0aB13LayoutManagerC04willC25VisibleLinesInContentView33_8A34A44A3A81F5AC1210A0E6DECBF3ABLLyyAA0abiJ0CF + 405
15  SourceEditor                        0x000000011827e527 $S12SourceEditor0aB13LayoutManagerC17layoutContentViewyyAA0abfG0CF + 103
16  SourceEditor                        0x000000011803e934 $S12SourceEditor0aB11ContentViewC15layoutSublayers2ofySo7CALayerC_tFTo + 68
17  QuartzCore                          0x00007fff4e2b8ec2 -[CALayer layoutSublayers] + 233
18  AppKit                              0x00007fff4099e095 _NSBackingLayerLayoutSublayers + 157
19  AppKit                              0x00007fff40a7c4ee -[_NSViewBackingLayer layoutSublayers] + 114
20  QuartzCore                          0x00007fff4e2b8a4f _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 395
21  QuartzCore                          0x00007fff4e2a743c _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 308
22  QuartzCore                          0x00007fff4e2a6d20 _ZN2CA11Transaction6commitEv + 576
23  AppKit                              0x00007fff409808f5 __65+[CATransaction(NSCATransaction) NS_setFlushesWithDisplayRefresh]_block_invoke + 274
24  CoreFoundation                      0x00007fff4338495d __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
25  CoreFoundation                      0x00007fff43384892 __CFRunLoopDoObservers + 452
26  CoreFoundation                      0x00007fff433263c5 __CFRunLoopRun + 1166
27  CoreFoundation                      0x00007fff43325ce4 CFRunLoopRunSpecific + 463
28  HIToolbox                           0x00007fff425bf895 RunCurrentEventLoopInMode + 293
29  HIToolbox                           0x00007fff425bf4d4 ReceiveNextEventCommon + 371
30  HIToolbox                           0x00007fff425bf348 _BlockUntilNextEventMatchingListInModeWithFilter + 64
31  AppKit                              0x00007fff4087c95b _DPSNextEvent + 997
32  AppKit                              0x00007fff4087b6fa -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1362
33  DVTKit                              0x00000001016f2b26 -[DVTApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 385
34  AppKit                              0x00007fff4087575d -[NSApplication run] + 699
35  AppKit                              0x00007fff40864e97 NSApplicationMain + 780
36  Xcode                               0x00000001009fc82e main + 574
37  libdyld.dylib                       0x00007fff703bb085 start + 1
38  ???                                 0x0000000000000002 0x0 + 2


Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   com.apple.AppKit              0x00007fff40c8a18f -[NSApplication _crashOnException:] + 109
1   com.apple.AppKit              0x00007fff40980b34 __65+[CATransaction(NSCATransaction) NS_setFlushesWithDisplayRefresh]_block_invoke + 849
2   com.apple.CoreFoundation      0x00007fff4338495d __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
3   com.apple.CoreFoundation      0x00007fff43384892 __CFRunLoopDoObservers + 452
4   com.apple.CoreFoundation      0x00007fff433263c5 __CFRunLoopRun + 1166
5   com.apple.CoreFoundation      0x00007fff43325ce4 CFRunLoopRunSpecific + 463
6   com.apple.HIToolbox            0x00007fff425bf895 RunCurrentEventLoopInMode + 293
7   com.apple.HIToolbox            0x00007fff425bf4d4 ReceiveNextEventCommon + 371
8   com.apple.HIToolbox            0x00007fff425bf348 _BlockUntilNextEventMatchingListInModeWithFilter + 64
9   com.apple.AppKit              0x00007fff4087c95b _DPSNextEvent + 997
10  com.apple.AppKit              0x00007fff4087b6fa -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1362
11  com.apple.dt.DVTKit            0x00000001016f2b26 -[DVTApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 385
12  com.apple.AppKit              0x00007fff4087575d -[NSApplication run] + 699
13  com.apple.AppKit              0x00007fff40864e97 NSApplicationMain + 780
14  com.apple.dt.Xcode            0x00000001009fc82e main + 574
15  libdyld.dylib                  0x00007fff703bb085 start + 1