diff --git a/boa_engine/src/context/mod.rs b/boa_engine/src/context/mod.rs
index 32dd3008f71..60eb6313abd 100644
--- a/boa_engine/src/context/mod.rs
+++ b/boa_engine/src/context/mod.rs
@@ -513,6 +513,23 @@ impl<'host> Context<'host> {
         std::mem::replace(&mut self.realm, realm)
     }
 
+    /// Create a new Realm with the default global bindings.
+    pub fn create_realm(&mut self) -> JsResult<Realm> {
+        let realm = Realm::create(&*self.host_hooks, &self.root_shape);
+
+        let old_realm = self.enter_realm(realm);
+
+        builtins::set_default_global_bindings(self)?;
+
+        Ok(self.enter_realm(old_realm))
+    }
+
+    /// Get the remaining instruction count
+    #[cfg(feature = "fuzz")]
+    #[inline]
+    pub const fn instructions_remaining(&self) -> usize {
+        self.instructions_remaining
+    }
     /// Get the [`RootShape`].
     #[inline]
     #[must_use]
diff --git a/boa_engine/src/error.rs b/boa_engine/src/error.rs
index 839f404c687..a103197d6b6 100644
--- a/boa_engine/src/error.rs
+++ b/boa_engine/src/error.rs
@@ -819,9 +819,7 @@ impl JsNativeError {
             JsNativeErrorKind::Uri => (constructors.uri_error().prototype(), ErrorKind::Uri),
             #[cfg(feature = "fuzz")]
             JsNativeErrorKind::NoInstructionsRemain => {
-                unreachable!(
-                    "The NoInstructionsRemain native error cannot be converted to an opaque type."
-                )
+                (constructors.eval_error().prototype(), ErrorKind::Eval)
             }
             JsNativeErrorKind::RuntimeLimit => {
                 panic!("The RuntimeLimit native error cannot be converted to an opaque type.")
diff --git a/boa_engine/src/value/conversions/serde_json.rs b/boa_engine/src/value/conversions/serde_json.rs
index f4f73f63eeb..4413333aaaf 100644
--- a/boa_engine/src/value/conversions/serde_json.rs
+++ b/boa_engine/src/value/conversions/serde_json.rs
@@ -108,14 +108,12 @@ impl JsValue {
     /// #
     /// # assert_eq!(json, back_to_json);
     /// ```
-    ///
-    /// # Panics
-    ///
-    /// Panics if the `JsValue` is `Undefined`.
     pub fn to_json(&self, context: &mut Context<'_>) -> JsResult<Value> {
         match self {
             Self::Null => Ok(Value::Null),
-            Self::Undefined => todo!("undefined to JSON"),
+            Self::Undefined => Err(JsNativeError::typ()
+                .with_message("cannot convert undefined to JSON")
+                .into()),
             &Self::Boolean(b) => Ok(b.into()),
             Self::String(string) => Ok(string.to_std_string_escaped().into()),
             &Self::Rational(rat) => Ok(rat.into()),
diff --git a/boa_gc/src/lib.rs b/boa_gc/src/lib.rs
index 698f6001bd8..90486557d2d 100644
--- a/boa_gc/src/lib.rs
+++ b/boa_gc/src/lib.rs
@@ -567,6 +567,18 @@ pub fn force_collect() {
     });
 }
 
+pub fn gc_reset() {
+    let new =  BoaGc {
+    config: GcConfig::default(),
+    runtime: GcRuntimeData::default(),
+    strong_start: Cell::new(None),
+    weak_start: Cell::new(None),
+    weak_map_start: Cell::new(None),
+};
+
+    BOA_GC.replace(new);
+}
+
 #[cfg(test)]
 mod test;