prune invalid refs when adding new ones

Author: jraymakers

api/src/DuckDBPreparedStatementWeakRefCollection.ts

@@ -6,6 +6,7 @@ export class DuckDBPreparedStatementWeakRefCollection
 {
   preparedStatements: WeakRef<DuckDBPreparedStatement>[] = [];
   public add(prepared: DuckDBPreparedStatement) {
+    this.prune();
     this.preparedStatements.push(new WeakRef(prepared));
   }
   public destroySync() {
@@ -17,4 +18,9 @@ export class DuckDBPreparedStatementWeakRefCollection
     }
     this.preparedStatements = [];
   }
+  private prune() {
+    this.preparedStatements = this.preparedStatements.filter(
+      (ref) => !!ref.deref()
+    );
+  }
 }