diff --git a/nix-js/runtime-ts/tsconfig.json b/nix-js/runtime-ts/tsconfig.json
index 3bd1cc1..b4bb5e7 100644
--- a/nix-js/runtime-ts/tsconfig.json
+++ b/nix-js/runtime-ts/tsconfig.json
@@ -1,8 +1,8 @@
 {
   "compilerOptions": {
-    "target": "ES2020",
+    "target": "ES2022",
     "module": "ESNext",
-    "lib": ["ES2020", "DOM"],
+    "lib": ["ES2022", "DOM"],
     "moduleResolution": "bundler",
     "strict": true,
     "noUnusedLocals": false,
diff --git a/nix-js/src/codegen.rs b/nix-js/src/codegen.rs
index 5634993..bfe6c30 100644
--- a/nix-js/src/codegen.rs
+++ b/nix-js/src/codegen.rs
@@ -65,7 +65,11 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Ir {
             Ir::Builtin(_) => "Nix.builtins".to_string(),
             Ir::ConcatStrings(x) => x.compile(ctx),
             Ir::HasAttr(x) => x.compile(ctx),
-            ir => todo!("{ir:?}"),
+            &Ir::Assert(Assert { assertion, expr }) => {
+                let assertion = ctx.get_ir(assertion).compile(ctx);
+                let expr = ctx.get_ir(expr).compile(ctx);
+                format!("({assertion})?({expr}):(()=>{{throw \"assertion failed\"}})()")
+            }
         }
     }
 }
diff --git a/nix-js/src/ir.rs b/nix-js/src/ir.rs
index d9ddbd2..c231245 100644
--- a/nix-js/src/ir.rs
+++ b/nix-js/src/ir.rs
@@ -50,7 +50,6 @@ ir! {
     Select,
     If,
     Call,
-    With,
     Assert,
     ConcatStrings,
     Const,
@@ -59,7 +58,6 @@ ir! {
     Func,
     Let,
     Arg(ArgId),
-    PrimOp(PrimOpId),
     ExprRef(ExprId),
     Thunk(ExprId),
     Builtin,
@@ -150,10 +148,6 @@ pub struct ExprId(pub usize);
 
 pub type SymId = SymbolU32;
 
-#[repr(transparent)]
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct PrimOpId(pub usize);
-
 #[repr(transparent)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct ArgId(pub usize);
@@ -342,15 +336,6 @@ pub struct Call {
     pub arg: ExprId,
 }
 
-/// Represents a `with` expression.
-#[derive(Debug)]
-pub struct With {
-    /// The namespace to bring into scope.
-    pub namespace: ExprId,
-    /// The expression to be evaluated within the new scope.
-    pub expr: ExprId,
-}
-
 /// Represents an `assert` expression.
 #[derive(Debug)]
 pub struct Assert {
diff --git a/nix-js/src/runtime.rs b/nix-js/src/runtime.rs
index dc2b3ab..28c9a2c 100644
--- a/nix-js/src/runtime.rs
+++ b/nix-js/src/runtime.rs
@@ -353,7 +353,7 @@ fn to_value<'a, 'b>(val: v8::Local<'a, v8::Value>, ctx: &RuntimeContext<'a, 'b>)
                 .collect();
             Value::AttrSet(AttrSet::new(attrs))
         }
-        _ => todo!("{}", val.type_repr()),
+        _ => unimplemented!("can not convert {} to NixValue", val.type_repr()),
     }
 }