AWS api-gateway authorization_scopes incorrect attribute value type

I’m using the following code for the API gateway and getting incorrect attribute value type.

resource “aws_api_gateway_method” “default” {
count = length(var.path_parts) > 0 ? length(var.path_parts) : 0

rest_api_id = aws_api_gateway_rest_api.default..id[0]
resource_id = aws_api_gateway_resource.default.
.id[count.index]
http_method = element(var.http_methods, count.index)
authorization = length(var.authorizations) > 0 ? element(var.authorizations, count.index) : “NONE”
authorizer_id = length(var.authorizer_ids) > 0 ? element(var.authorizer_ids, count.index) : null
authorization_scopes = length(var.authorization_scopes) > 0 ? element(var.authorization_scopes, count.index) : null
api_key_required = length(var.api_key_requireds) > 0 ? element(var.api_key_requireds, count.index) : null
request_models = length(var.request_models) > 0 ? element(var.request_models, count.index) : { “application/json” = “Empty” }
request_validator_id = length(var.request_validator_ids) > 0 ? element(var.request_validator_ids, count.index) : null
request_parameters = length(var.request_parameters) > 0 ? element(var.request_parameters, count.index) : {}

ERROR:
authorization_scopes = length(var.authorization_scopes) > 0 ? element(var.authorization_scopes, count.index) : null

Inappropriate value for attribute “authorization_scopes”: set of string
required.

any help on this would help