core: cover errors in handler setup()

Change-Id: I0bb2f07e26717205c013dfedec6e1beca2947d17
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/33239
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Alexander Zaft <a.zaft@fz-juelich.de>

frappy/protocol/interface/handler.py

@@ -61,10 +61,16 @@ class RequestHandler:
         self.request = request
         self.client_address = client_address
         self.server = server
+        self.log = None
 
-        self.setup()
         try:
+            self.setup()
             self.handle()
+        except Exception:
+            if self.log:
+                self.log.error(formatException())
+            else:
+                server.log.error(formatException())
         finally:
             self.finish()