WIP: Try and remember that the server quit

autoload/vimspector/internal/channel.vim

@@ -40,6 +40,7 @@ endfunction
 
 function! s:_Send( msg ) abort
   call ch_sendraw( s:ch, a:msg )
+  return 1
 endfunction
 
 function! vimspector#internal#channel#Timeout( id ) abort

autoload/vimspector/internal/job.vim

@@ -43,21 +43,22 @@ endfunction
 function! s:_Send( msg ) abort
   if ! exists( 's:job' )
     echom "Can't send message: Job was not initialised correctly"
-    return
+    return 0
   endif
 
   if job_status( s:job ) != 'run'
     echom "Can't send message: Job is not running"
-    return
+    return 0
   endif
 
   let ch = job_getchannel( s:job )
   if ch == 'channel fail'
     echom "Channel was closed unexpectedly!"
-    return
+    return 0
   endif
 
   call ch_sendraw( ch, a:msg )
+  return 1
 endfunction
 
 function! vimspector#internal#job#StartDebugSession( config ) abort

python3/vimspector/debug_adapter_connection.py

@@ -56,11 +56,14 @@ class DebugAdapterConnection( object ):
       'timer_start( {}, "vimspector#internal#channel#Timeout" )'.format(
         timeout ) )
 
-    self._outstanding_requests[ this_id ] = PendingRequest( msg,
-                                                            handler,
-                                                            failure_handler,
-                                                            expiry_id )
-    self._SendMessage( msg )
+    request = PendingRequest( msg,
+                              handler,
+                              failure_handler,
+                              expiry_id )
+    self._outstanding_requests[ this_id ] = request
+
+    if not self._SendMessage( msg ):
+      self._AbortRequest( request, 'Unable to send message' )
 
   def OnRequestTimeout( self, timer_id ):
     request_id = None
@@ -144,7 +147,7 @@ class DebugAdapterConnection( object ):
 
     data = 'Content-Length: {0}\r\n\r\n{1}'.format( len( msg ), msg )
     # self._logger.debug( 'Sending: {0}'.format( data ) )
-    self._Write( data )
+    return self._Write( data )
 
   def _ReadHeaders( self ):
     parts = self._buffer.split( bytes( '\r\n\r\n', 'utf-8' ), 1 )

python3/vimspector/debug_session.py

@@ -578,6 +578,7 @@ class DebugSession( object ):
 
   def OnEvent_terminated( self, message ):
     self.Clear()
+    self._connection = None
     utils.UserMessage( "Debugging was terminated." )
 
   def _RemoveBreakpoints( self ):