Use named field initialization for references

src/libexpr/primops.cc

@@ -1249,7 +1249,7 @@ static void prim_derivationStrict(EvalState & state, const PosIdx pos, Value * *
                 .method = method,
                 .hash = h,
             },
-            {},
+            .references = {},
         });
         drv.env["out"] = state.store->printStorePath(outPath);
         drv.outputs.insert_or_assign("out",

src/libexpr/primops/fetchTree.cc

@@ -235,7 +235,7 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
                     .method = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat,
                     .hash = *expectedHash,
                 },
-                {}
+                .references = {}
             });
 
         if (state.store->isValidPath(expectedPath)) {