I get this error from the AWS RouteTable Association but based on the doc its not needed.

error: 1 error occurred:
        * creating urn:pulumi:lab::CorpSystemsAWSAccount::aws:ec2/routeTable:RouteTable::privatertAWest: 1 error occurred:
        * error creating route: one of `carrier_gateway_id, core_network_arn, egress_only_gateway_id, gateway_id, instance_id, local_gateway_id, nat_gateway_id, network_interface_id, transit_gateway_id, vpc_endpoint_id, vpc_peering_connection_id` must be specified

Are you asking about RouteTable or RouteTableAssociation? Your code (assuming the previous Slack message is related) uses RouteTable, but your question was related to RouteTableAssociation (and the error message references RouteTable as well).

the association....seems to think I need to say it needs a gatewayid

A RouteTableAssociation needs either a subnet ID or a gateway ID

well when I delete the association the rt is created