refactor: Remove redundant validation

Only extension validation is needed

hugr/src/hugr.rs

@@ -8,6 +8,8 @@ pub mod serialize;
 pub mod validate;
 pub mod views;
 
+#[cfg(feature = "extension_inference")]
+use std::collections::HashMap;
 use std::collections::VecDeque;
 use std::iter;
 
@@ -198,7 +200,8 @@ impl Hugr {
         resolve_extension_ops(self, extension_registry)?;
         self.validate_no_extensions(extension_registry)?;
         self.infer_extensions()?;
-        self.validate(extension_registry)?;
+        #[cfg(feature = "infer_extensions")]
+        self.validate_extensions(HashMap::new())?;
         Ok(())
     }