【求助】5.0.2-beta 版本 iOS13.4.1 HandyJSON.toJSONString() crash

Crashed: com.xxxx.ioqueue
0 libobjc.A.dylib 0x18cd65b30 objc_msgSend + 16
1 libswiftCore.dylib 0x19a534200 __CocoaDictionary.Iterator.nextKey() + 64
2 libswiftCore.dylib 0x19a534758 __CocoaDictionary.Iterator.next() + 24
3 HandyJSON 0x104154990 $sSD9HandyJSONE11_plainValueypSgyF + 1252
4 HandyJSON 0x1041724cc $s9HandyJSON14_TransformablePAAE10plainValueypSgyF + 472
5 HandyJSON 0x104152d6c $sSq9HandyJSONE11_plainValueypSgyF + 256
6 HandyJSON 0x1041724cc $s9HandyJSON14_TransformablePAAE10plainValueypSgyF + 472
7 HandyJSON 0x104162a90 $s9HandyJSON22_ExtendCustomModelTypePAAE13_serializeAny6objectypSgAA14_Transformable_p_tFZ + 1236
8 HandyJSON 0x104163a58 $s9HandyJSON22_ExtendCustomModelTypePAAE010_serializeE6Object8instance10properties6mapperSDySSypGAaB_p_SDySSyp_AA12PropertyInfoVSgtGAA13HelpingMapperCtFZ + 1892
9 HandyJSON 0x104163240 $s9HandyJSON22_ExtendCustomModelTypePAAE13_serializeAny6objectypSgAA14_Transformable_p_tFZ + 3204
10 HandyJSON 0x104163a58 $s9HandyJSON22_ExtendCustomModelTypePAAE010_serializeE6Object8instance10properties6mapperSDySSypGAaB_p_SDySSyp_AA12PropertyInfoVSgtGAA13HelpingMapperCtFZ + 1892
11 HandyJSON 0x104163240 $s9HandyJSON22_ExtendCustomModelTypePAAE13_serializeAny6objectypSgAA14_Transformable_p_tFZ + 3204
12 HandyJSON 0x104170570 $s9HandyJSONAAPAAE02toB0SDySSypGSgyF + 92
13 HandyJSON 0x104170668 $s9HandyJSONAAPAAE12toJSONString11prettyPrintSSSgSb_tF + 92
14 Sudoku 0x1026db418 specialized static JSONDataManager.write(data:toDocument:sandboxType:) + 41 (JSONDataManager.swift:41)
15 Sudoku 0x10269b048 closure #1 in UserDataManager.saveOperationRecrod(isAsync:) + 4306858056 (:4306858056)
16 Sudoku 0x1026a0614 partial apply for closure #2 in UserDataManager.saveSettings(isAsync:) + 4306880020 (:4306880020)
17 Sudoku 0x102698d98 thunk for @escaping @callee_guaranteed () -> () + 4306849176 (:4306849176)
18 libdispatch.dylib 0x18cd0c9a8 _dispatch_call_block_and_release + 24
19 libdispatch.dylib 0x18cd0d524 _dispatch_client_callout + 16
20 libdispatch.dylib 0x18ccb98a4 _dispatch_lane_serial_drain$VARIANT$mp + 608
21 libdispatch.dylib 0x18ccba2c4 _dispatch_lane_invoke$VARIANT$mp + 464
22 libdispatch.dylib 0x18ccc378c _dispatch_workloop_worker_thread + 588
23 libsystem_pthread.dylib 0x18cd5eb74 _pthread_wqthread + 272
24 libsystem_pthread.dylib 0x18cd61740 start_wqthread + 8

Start at the HandyJSON.toJSONString() call in the crash stack and inspect the _plainValue and serialization paths, with the reported call site in JSONDataManager.swift:41 as the reproduction entry point. Reproduce the crash on iOS 13.4.1 using HandyJSON 5.0.2-beta, then verify that the same data serializes without crashing.

Written by the indexing model from the issue text.