Fix racing merge breakage (#5472)

Author: kripken

src/passes/RemoveUnusedModuleElements.cpp

@@ -285,9 +285,6 @@ struct Analyzer {
     }
   }
 
-  // We'll compute SubTypes if we need them.
-  std::optional<SubTypes> subTypes;
-
   // Process expressions in the expression queue while we have any, visiting
   // them (using their contents) and adding children. Returns whether we did any
   // work.
@@ -326,6 +323,7 @@ struct Analyzer {
     return worked;
   }
 
+  // We'll compute SubTypes if we need them.
   std::optional<SubTypes> subTypes;
 
   void useCallRefType(HeapType type) {