More work on switching battle data to interior mutability, instead of exterior mutability.

tests/common/library_loader.rs

@@ -188,9 +188,13 @@ pub fn load_moves(path: &String, lib: &mut StaticData) {
                 }
             }
 
-            SecondaryEffect::new(chance, StringKey::new(v["name"].as_str().unwrap()), parameters)
+            Some(SecondaryEffect::new(
+                chance,
+                StringKey::new(v["name"].as_str().unwrap()),
+                parameters,
+            ))
         } else {
-            SecondaryEffect::empty()
+            None
         };
 
         let mut flags = HashSet::new();