do not require empty string for optional field

Author: internet-diglett

wicket/src/cli/rack_setup/config_template.toml

@@ -57,7 +57,6 @@ allow = "any"
 
 # TODO: docs on network config
 [rack_network_config]
-rack_subnet_address = ""
 infra_ip_first = ""
 infra_ip_last = ""
 

wicket/src/cli/rack_setup/config_toml.rs

@@ -245,12 +245,15 @@ fn populate_network_table(
     };
 
     if let Some(rack_subnet_address) = config.rack_subnet_address {
-        *table
-            .get_mut("rack_subnet_address")
-            .unwrap()
-            .as_value_mut()
-            .unwrap() =
-            Value::String(Formatted::new(rack_subnet_address.to_string()));
+        let value = Value::String(Formatted::new(rack_subnet_address.to_string()));
+        match table.entry("rack_subnet_address") {
+            toml_edit::Entry::Occupied(mut entry) => {
+                entry.insert( Item::Value(value));
+            },
+            toml_edit::Entry::Vacant(entry) => {
+                entry.insert(Item::Value(value));
+            },
+        }
     }
 
     for (property, value) in [

wicket/tests/output/example_non_empty.toml

@@ -69,9 +69,9 @@ allow = "any"
 
 # TODO: docs on network config
 [rack_network_config]
-rack_subnet_address = "fd00:1122:3344:100::"
 infra_ip_first = "172.30.0.1"
 infra_ip_last = "172.30.0.10"
+rack_subnet_address = "fd00:1122:3344:100::"
 
 [rack_network_config.switch0.port0]
 routes = [{ nexthop = "172.30.0.10", destination = "0.0.0.0/0", vlan_id = 1 }]