fix: don't allow strict-server to be used on its own

As it doesn't actually do anything, as it wraps an existing server i.e.
Chi.

Closes #1558.

pkg/codegen/configuration.go

@@ -185,5 +185,10 @@ func (o Configuration) Validate() error {
  if nServers > 1 {
  return errors.New("only one server type is supported at a time")
  }
+
+ if o.Generate.Strict && nServers == 0 {
+ return errors.New("the `strict-server` option is added in addition to another server to be generated. Adding `strict-server` on its own will not generate anything")
+ }
+
  return nil
 }