avoid duplicates in output assets list

Author: sokra

crates/next-core/src/emit.rs

@@ -1,4 +1,5 @@
 use anyhow::Result;
+use rustc_hash::FxHashSet;
 use tracing::Instrument;
 use turbo_tasks::{
     graph::{AdjacencyMap, GraphTraversal},
@@ -112,6 +113,8 @@ pub async fn all_assets_from_entries(entries: Vc<OutputAssets>) -> Result<Vc<Out
             .completed()?
             .into_inner()
             .into_reverse_topological()
+            .collect::<FxHashSet<_>>()
+            .into_iter()
             .collect(),
     ))
 }