[execution][algorithm] Improve error handling during process

If process fails, return early and send done message to
other parties. This allows to stop everything more
cleanly.

beat/backend/python/execution/algorithm.py

@@ -256,14 +256,18 @@ class AlgorithmExecutor(object):
                             output=self.output_list[0],
                         )
                     else:
-                        result = self.runner.process(
-                            inputs=self.input_list,
-                            data_loaders=self.data_loaders,
-                            outputs=self.output_list,
-                            loop_channel=self.loop_channel,
-                        )
+                        try:
+                            result = self.runner.process(
+                                inputs=self.input_list,
+                                data_loaders=self.data_loaders,
+                                outputs=self.output_list,
+                                loop_channel=self.loop_channel,
+                            )
+                        except Exception:
+                            result = None
 
                 if not result:
+                    self.done({})
                     return False
 
         for output in self.output_list: