component AP gateway: properly close the HTTP connection on checkSignature exception:

if something is going wrong during `checkSignature` (other than signature verification
failing), a `500 Internal Server Error` code is returned, and the connection is properly
closed.

sat/plugins/plugin_comp_ap_gateway/http_server.py

@@ -1049,6 +1049,14 @@ class HTTPAPGServer(web_resource.Resource):
             )
             request.finish()
             return
+        except Exception as e:
+            self.responseCode(
+                request,
+                http.INTERNAL_SERVER_ERROR,
+                f"Can't check signature: {e}"
+            )
+            request.finish()
+            return
 
         request.setResponseCode(http.ACCEPTED)