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> Can you tell why I'm getting this exception?                                  
                                                                                
24/03/2026 14:13:16 sttwinservice.exe 12.29 <Start of exception log>            
  Address: 0000000002C2FB7E                                                     
  Description: Application Error: Exception EAccessViolation in module          
sttwinservice.exe at 000000000275FB7E.                                          
 Access violation at address 0000000002C2FB7E in module 'sttwinservice.exe'     
(offset 275FB7E). Read of address 0000000000000000.                             
                                                                                
  Thread: TGpTcpNewforServerThread (16816)                                      
  Main thread: 16660                                                            
  Program started at: 2026-03-24 12:54:16 [local], 2026-03-24 11:54:16 [UTC]    
  Uptime: 1 hours                                                               
  Command line: "C:\Program Files\FAB Subtitler Server\sttwinservice.exe"       
  Build: Release                                                                
  Working set: 1,5 GB [3,9 GB max]                                              
  Page file: 11,7 GB [12,9 GB max]                                              
  Virtual memory: 117,2 GB / 131.072,0 GB                                       
  ---                                                                           
  Physical memory: 7,8 GB / 63,6 GB                                             
  Page file: 19,0 GB / 67,6 GB                                                  
  Debug info: JCL                                                               
  Exception location: FABWhisperLive.pas, line 379                              
TWhisperLiveWorker.ForwardNewforInfo_Asy @0000000002C2FB7E                      
    FILE                        LINE PROCEDURE                                  
                                   ADDRESS   SP                                 
  ------ stackwalk trace ------------------------------------------------------ 
---------------------------------------------------------                       
                                   0 ZwGetContextThread                         
                                   @00007FFF3DA639E4 0000000000000000           
    JclDebug                    5724 TJclStackInfoList.Create                   
                                   @0000000000A829F4 0000000000000000           
    GpExcept                    1805 JclCreateThreadStackTraceLocal             
                                   @0000000000B6FC6A 0000000000000000           
    GpExcept                    1814 GetExceptionStackInfo                      
                                   @0000000000B6FCC5 0000000000000000           
    System.SysUtils                0 Exception.RaisingException                 
                                   @0000000000527A87 0000000000000000           
    System.SysUtils                0 GetExceptionObject                         
                                   @0000000000528B87 0000000000000000           
    JclHookExcept                314 DoExceptFilter                             
                                   @0000000000A71D2A 0000000000000000           
    JclHookExcept                393 HookedExceptObjProc                        
                                   @0000000000A72031 0000000000000000           
    System                         0 @DelphiExceptionHandler                    
                                                                                
… +253 lines …                                                                  
------ stackwalk trace -------------------------------------------------------- 
-------------------------------------------------------                         
                                   0 ZwWaitForMultipleObjects                   
                                   @00007FFF3DA625E4 00000000C52FF650           
                                   0 WaitForMultipleObjectsEx                   
                                   @00007FFF3B191A93 00000000C52FF658           
    GpSharedMemory               292 .TGpSharedMemory                           
                                   @0000000000A3EE08 00000000C52FF668           
    GpSharedMemory              1343 TGpBaseSharedMemory.GetHuge                
                                   @0000000000A410E4 00000000C52FF678           
                                                                                
  Thread: OmniThreadPool manager GlobalOmniThreadPool (16716) (suspended)       
    FILE                        LINE PROCEDURE                                  
                                   ADDRESS   SP                                 
  ------ stackwalk trace ------------------------------------------------------ 
---------------------------------------------------------                       
                                   0 NtUserMsgWaitForMultipleObjectsEx          
                                   @00007FFF3B12AD74 00000000C51FF910           
    OtlSync                     2275 TWaitFor.MsgWaitAny                        
                                   @000000000098D621 00000000C51FF918           
    OtlSync                     1277 TOmniCriticalSection.Release               
                                   @000000000098C529 00000000C51FF938           
    OtlSync                        0 .TWaitFor.TWaiter                          
                                   @000000000098B2D8 00000000C51FF948           
    OtlTaskControl              3118 TOmniTaskExecutor.WaitForEvent             
                                   @00000000009E66BB 00000000C51FF998           
                                                                                
  Thread: sttwinservice (16660) (suspended)                                     
    FILE                        LINE PROCEDURE                                  
                                   ADDRESS   SP                                 
  ------ stackwalk trace ------------------------------------------------------ 
---------------------------------------------------------                       
                                   0 NtUserWaitMessage                          
                                   @00007FFF3B1213F4 00000000C4B2F8C0           
    Vcl.Forms                      0 TApplication.Idle                          
                                   @00000000008939C8 00000000C4B2F8C8           
24/03/2026 14:13:17 sttwinservice.exe 12.29 <End of exception log>              

● Let me look at the relevant source files.

  Searched for 3 patterns, read 2 files (ctrl+o to expand)

● The crash is on line 379: wi.AudioReceiver.Stop — wi.AudioReceiver is nil.

  Looking at the logic: wi.HasActiveClient is set to false on line 378, and
  wi.AudioReceiver is set to nil on line 380 — but the crash is on line 379,
  meaning AudioReceiver is already nil before this code even runs.

  This means a disconnect event fired for a client that was already cleaned up —
   i.e., FClientToEngine.TryGetValue found an entry, but the TWhisperInfo it
  points to already had AudioReceiver = nil from a previous cleanup.

  The likely cause: double disconnect. A client disconnected, cleanup ran
  (including wi.AudioReceiver := nil), but somehow FClientToEngine still has the
   entry for that ClientID. Then a second disconnect event for the same client
  fires, TryGetValue succeeds again, and it tries to call .Stop on the
  already-nil AudioReceiver.

  The missing guard is: AudioReceiver should be checked before calling .Stop. Or
   better, FClientToEngine.Remove on line 363 should prevent re-entry — but
  Remove is called inside FHandshakeGuard, so if there's a second disconnect
  that races through before the first Remove, both could enter and the second
  would find idxEngine and a nil AudioReceiver.

  Wait — actually FHandshakeGuard.Acquire serializes them, so the second call
  would not find the entry (it was already removed on line 363 by the first).
  That means it's something else...

  Could there be a path where AudioReceiver legitimately becomes nil without
  removing the FClientToEngine entry? For example, if the handshake never
  completed and AudioReceiver was never assigned but the engine index was still
  mapped.

  The simplest fix:

  if assigned(wi.AudioReceiver) then begin
    wi.AudioReceiver.Stop;
    wi.AudioReceiver := nil;
  end;

  But to understand the root cause fully — do you have other code that sets
  AudioReceiver := nil without also removing from FClientToEngine? Let me check:

  Searched for 2 patterns, read 1 file (ctrl+o to expand)

● Now the picture is complete. Here's the bug:

  Root cause: FClientToEngine is populated on line 284 (during engine 
  assignment), but wi.AudioReceiver is only assigned later on line 657 (when the
   client sends the start-transcription command). If the client disconnects in
  the window between these two events — i.e., the engine was assigned but the
  start command never arrived — then wi.AudioReceiver is still nil, but
  FClientToEngine has the entry.

  When disconnect fires → ForwardNewforInfo_Asy → TryGetValue succeeds →
  wi.AudioReceiver.Stop → crash on nil.

  The fix is to guard the call on line 379:

  if assigned(wi.AudioReceiver) then begin
    wi.AudioReceiver.Stop;
    wi.AudioReceiver := nil;
  end;

  The wi.AudioReceiver := nil on line 380 is already outside this guard since
  nil-ing a nil interface is harmless, but for clarity it makes sense to move it
   inside the if block too.

✻ Cooked for 59s