Add back thread observer

Author: npezza93

lib/solid_queue/pool.rb

@@ -19,18 +19,18 @@ def post(execution)
       available_threads.decrement
 
       future = Concurrent::Future.new(args: [ execution ], executor: executor) do |thread_execution|
-        begin
-          wrap_in_app_executor do
-            thread_execution.perform
-          end
-        rescue Exception
-          nil
+        wrap_in_app_executor do
+          thread_execution.perform
         ensure
           available_threads.increment
           mutex.synchronize { on_idle.try(:call) if idle? }
         end
       end
 
+      future.add_observer do |_, _, error|
+        handle_thread_error(error) if error
+      end
+
       future.execute
     end