Odd evenstore <-> postgrex error

Formatted_error.ex

%Postgrex.Error{
	connection_id: 17550, 
	message: nil, 
	postgres: %{
		code: :object_not_in_prerequisite_state, 
		detail: "The tuple structure of a not-yet-assigned record is indeterminate.", 
		file: "pl_exec.c", 
		line: "4905", 
		message: "record \"old\" is not assigned yet", 
		pg_code: "55000", 
		routine: "exec_eval_datum", 
		severity: "ERROR", 
		unknown: "ERROR", 
		where: "PL/pgSQL function notify_events() line 14 at assignment"
	}, 
	query: nil

Full_traceback.ex

 12:55:26.837 [error] ** (MatchError) no match of right hand side value: %Postgrex.Error{connection_id: 17550, message: nil, postgres: %{code: :object_not_in_prerequisite_state, detail: "The tuple structure of a not-yet-assigned record is indeterminate.", file: "pl_exec.c", line: "4905", message: "record \"old\" is not assigned yet", pg_code: "55000", routine: "exec_eval_datum", severity: "ERROR", unknown: "ERROR", where: "PL/pgSQL function notify_events() line 14 at assignment"}, query: nil}
         (eventstore 1.3.1) lib/event_store/storage/appender.ex:159: EventStore.Storage.Appender.handle_response/1
         (eventstore 1.3.1) lib/event_store/storage/appender.ex:27: anonymous fn/5 in EventStore.Storage.Appender.append/4
         (elixir 1.11.4) lib/enum.ex:804: anonymous fn/3 in Enum.each/2
         (elixir 1.11.4) lib/enum.ex:3473: anonymous fn/3 in Enum.each/2
         (elixir 1.11.4) lib/stream.ex:1597: anonymous fn/3 in Enumerable.Stream.reduce/3
         (elixir 1.11.4) lib/stream.ex:285: Stream.after_chunk_while/2
         (elixir 1.11.4) lib/stream.ex:1626: Enumerable.Stream.do_done/2
         (elixir 1.11.4) lib/enum.ex:3473: Enum.each/2
         (eventstore 1.3.1) lib/event_store/storage/appender.ex:24: EventStore.Storage.Appender.append/4
         (eventstore 1.3.1) lib/event_store/streams/stream.ex:12: EventStore.Streams.Stream.append_to_stream/5
         (commanded 1.2.0) lib/commanded/aggregates/aggregate.ex:491: Commanded.Aggregates.Aggregate.persist_events/4
         (commanded 1.2.0) lib/commanded/aggregates/aggregate.ex:466: Commanded.Aggregates.Aggregate.execute_command/2
         (commanded 1.2.0) lib/commanded/aggregates/aggregate.ex:231: Commanded.Aggregates.Aggregate.handle_call/3
         (stdlib 3.15) gen_server.erl:721: :gen_server.try_handle_call/4
         (stdlib 3.15) gen_server.erl:750: :gen_server.handle_msg/6
         (stdlib 3.15) proc_lib.erl:226: :proc_lib.init_p_do_apply/3