I have a lambda ion that is being invoked by an EventBride Schedule. The lambda is invoked correctly but the ion fails to run. The Cloudwatch log for the lambda shows this error:

Assert failed: (inst? t-last): datomic.ion.lambda.handler.exceptions.Incorrect
clojure.lang.ExceptionInfo: Assert failed: (inst? t-last) {:cognitect.anomalies/category :cognitect.anomalies/incorrect, :cognitect.anomalies/message "Assert failed: (inst? t-last)"}
	at datomic.ion.lambda.handler$throw_anomaly.invokeStatic(handler.clj:25)
	at datomic.ion.lambda.handler$throw_anomaly.invoke(handler.clj:21)
	at datomic.ion.lambda.handler.Handler.on_anomaly(handler.clj:175)
	at datomic.ion.lambda.handler.Handler.handle_request(handler.clj:205)
	at datomic.ion.lambda.handler$fn__3856$G__3781__3861.invoke(handler.clj:68)
	at datomic.ion.lambda.handler$fn__3856$G__3780__3867.invoke(handler.clj:68)
	at clojure.lang.Var.invoke(Var.java:399)
	at datomic.ion.lambda.handler.Thunk.handleRequest(Thunk.java:35)