diff --git a/crates/backend/src/typegen.rs b/crates/backend/src/typegen.rs
index 81f9fdf0..39e77169 100644
--- a/crates/backend/src/typegen.rs
+++ b/crates/backend/src/typegen.rs
@@ -64,7 +64,7 @@ pub fn ty_to_ts_type(ty: &Type) -> String {
 
 pub fn str_to_ts_type(ty: &str) -> String {
   match ty {
-    "()" => "null".to_owned(),
+    "()" => "undefined".to_owned(),
     "i8" | "i16" | "i32" | "i64" | "u8" | "u16" | "u32" => "number".to_owned(),
     "i128" | "isize" | "u64" | "u128" | "usize" => "BigInt".to_owned(),
     "bool" => "boolean".to_owned(),
@@ -82,7 +82,7 @@ pub fn str_to_ts_type(ty: &str) -> String {
       let captures = TYPE_REGEXES["Option"].captures(s).unwrap();
       let inner = captures.get(1).unwrap().as_str();
 
-      format!("{} | undefined", str_to_ts_type(inner))
+      format!("{} | null", str_to_ts_type(inner))
     }
     s if s.starts_with("Result") && TYPE_REGEXES["Result"].is_match(s) => {
       let captures = TYPE_REGEXES["Result"].captures(s).unwrap();
diff --git a/crates/napi/src/bindgen_runtime/js_values.rs b/crates/napi/src/bindgen_runtime/js_values.rs
index 7561c044..8946ad54 100644
--- a/crates/napi/src/bindgen_runtime/js_values.rs
+++ b/crates/napi/src/bindgen_runtime/js_values.rs
@@ -95,10 +95,7 @@ pub trait ValidateNapiValue: FromNapiValue + TypeName {
   }
 }
 
-impl<T> TypeName for Option<T>
-where
-  T: TypeName,
-{
+impl<T> TypeName for Option<T> {
   fn type_name() -> &'static str {
     "Option"
   }
@@ -106,19 +103,18 @@ where
 
 impl<T> FromNapiValue for Option<T>
 where
-  T: FromNapiValue + TypeName,
+  T: FromNapiValue,
 {
   unsafe fn from_napi_value(env: sys::napi_env, napi_val: sys::napi_value) -> Result<Self> {
     let mut val_type = 0;
 
     check_status!(
       sys::napi_typeof(env, napi_val, &mut val_type),
-      "Failed to convert napi value into rust type `Option<{}>`",
-      T::type_name()
+      "Failed to convert napi value into rust type `Option<T>`",
     )?;
 
     match val_type {
-      sys::ValueType::napi_undefined => Ok(None),
+      sys::ValueType::napi_undefined | sys::ValueType::napi_null => Ok(None),
       _ => Ok(Some(T::from_napi_value(env, napi_val)?)),
     }
   }
@@ -126,7 +122,7 @@ where
 
 impl<T> ToNapiValue for Option<T>
 where
-  T: ToNapiValue + TypeName,
+  T: ToNapiValue,
 {
   unsafe fn to_napi_value(env: sys::napi_env, val: Self) -> Result<sys::napi_value> {
     match val {
@@ -134,12 +130,33 @@ where
       None => {
         let mut ptr = ptr::null_mut();
         check_status!(
-          sys::napi_get_undefined(env, &mut ptr),
-          "Failed to convert rust type `Option<{}>` into napi value",
-          T::type_name(),
+          sys::napi_get_null(env, &mut ptr),
+          "Failed to convert rust type `Option<T>` into napi value",
         )?;
         Ok(ptr)
       }
     }
   }
 }
+
+impl<T> ToNapiValue for Result<T>
+where
+  T: ToNapiValue,
+{
+  unsafe fn to_napi_value(env: sys::napi_env, val: Self) -> Result<sys::napi_value> {
+    match val {
+      Ok(v) => T::to_napi_value(env, v),
+      Err(e) => {
+        let error_code = String::to_napi_value(env, format!("{:?}", e.status))?;
+        let reason = String::to_napi_value(env, e.reason)?;
+        let mut error = ptr::null_mut();
+        check_status!(
+          sys::napi_create_error(env, error_code, reason, &mut error),
+          "Failed to create napi error"
+        )?;
+
+        Ok(error)
+      }
+    }
+  }
+}
diff --git a/crates/napi/src/bindgen_runtime/js_values/nil.rs b/crates/napi/src/bindgen_runtime/js_values/nil.rs
index 05bd00f0..50177192 100644
--- a/crates/napi/src/bindgen_runtime/js_values/nil.rs
+++ b/crates/napi/src/bindgen_runtime/js_values/nil.rs
@@ -79,22 +79,3 @@ impl ToNapiValue for Undefined {
     Ok(ret)
   }
 }
-
-impl ToNapiValue for Result<()> {
-  unsafe fn to_napi_value(env: sys::napi_env, val: Self) -> Result<sys::napi_value> {
-    match val {
-      Ok(_) => Ok(Null::to_napi_value(env, Null).unwrap_or_else(|_| ptr::null_mut())),
-      Err(e) => {
-        let error_code = String::to_napi_value(env, format!("{:?}", e.status))?;
-        let reason = String::to_napi_value(env, e.reason)?;
-        let mut error = ptr::null_mut();
-        check_status!(
-          sys::napi_create_error(env, error_code, reason, &mut error),
-          "Failed to create napi error"
-        )?;
-
-        Ok(error)
-      }
-    }
-  }
-}
diff --git a/examples/napi/__test__/typegen.spec.ts.md b/examples/napi/__test__/typegen.spec.ts.md
index b17746ee..ae4d3aaf 100644
--- a/examples/napi/__test__/typegen.spec.ts.md
+++ b/examples/napi/__test__/typegen.spec.ts.md
@@ -12,11 +12,12 @@ Generated by [AVA](https://avajs.dev).
     export function getNums(): Array<number>␊
     export function sumNums(nums: Array<number>): number␊
     export function getCwd(callback: (arg0: string) => void): void␊
-    export function readFile(callback: (arg0: Error | null, arg1: string | undefined) => void): void␊
+    export function readFile(callback: (arg0: Error | undefined, arg1: string | null) => void): void␊
     export enum Kind { Dog = 0, Cat = 1, Duck = 2 }␊
     export enum CustomNumEnum { One = 1, Two = 2, Three = 3, Four = 4, Six = 6, Eight = 8, Nine = 9, Ten = 10 }␊
     export function enumToI32(e: CustomNumEnum): number␊
-    export function mapOption(val: number | undefined): number | undefined␊
+    export function getError(): Error | undefined␊
+    export function mapOption(val: number | null): number | null␊
     export function add(a: number, b: number): number␊
     export function fibonacci(n: number): number␊
     export function listObjKeys(obj: object): Array<string>␊
diff --git a/examples/napi/__test__/typegen.spec.ts.snap b/examples/napi/__test__/typegen.spec.ts.snap
index 81dd14dd..39980d0c 100644
Binary files a/examples/napi/__test__/typegen.spec.ts.snap and b/examples/napi/__test__/typegen.spec.ts.snap differ
diff --git a/examples/napi/__test__/values.spec.ts b/examples/napi/__test__/values.spec.ts
index f87f1144..c7487f0a 100644
--- a/examples/napi/__test__/values.spec.ts
+++ b/examples/napi/__test__/values.spec.ts
@@ -19,6 +19,7 @@ import {
   createObj,
   mapOption,
   readFile,
+  getError,
 } from '../'
 
 test('number', (t) => {
@@ -81,7 +82,7 @@ test('callback', (t) => {
   )
 
   readFile((err, content) => {
-    t.is(err, null)
+    t.is(err, undefined)
     t.is(content, 'hello world')
   })
 })
@@ -92,6 +93,12 @@ test('object', (t) => {
 })
 
 test('Option', (t) => {
-  t.is(mapOption(undefined), undefined)
+  t.is(mapOption(null), null)
   t.is(mapOption(3), 4)
 })
+
+test('Result', (t) => {
+  const error = getError()
+  t.not(error, undefined)
+  t.is(error!.message, 'Manual Error')
+})
diff --git a/examples/napi/index.d.ts b/examples/napi/index.d.ts
index 7cdb1527..7cbb680f 100644
--- a/examples/napi/index.d.ts
+++ b/examples/napi/index.d.ts
@@ -2,11 +2,12 @@ export function getWords(): Array<string>
 export function getNums(): Array<number>
 export function sumNums(nums: Array<number>): number
 export function getCwd(callback: (arg0: string) => void): void
-export function readFile(callback: (arg0: Error | null, arg1: string | undefined) => void): void
+export function readFile(callback: (arg0: Error | undefined, arg1: string | null) => void): void
 export enum Kind { Dog = 0, Cat = 1, Duck = 2 }
 export enum CustomNumEnum { One = 1, Two = 2, Three = 3, Four = 4, Six = 6, Eight = 8, Nine = 9, Ten = 10 }
 export function enumToI32(e: CustomNumEnum): number
-export function mapOption(val: number | undefined): number | undefined
+export function getError(): Error | undefined
+export function mapOption(val: number | null): number | null
 export function add(a: number, b: number): number
 export function fibonacci(n: number): number
 export function listObjKeys(obj: object): Array<string>
diff --git a/examples/napi/src/error.rs b/examples/napi/src/error.rs
new file mode 100644
index 00000000..31ce7e4b
--- /dev/null
+++ b/examples/napi/src/error.rs
@@ -0,0 +1,6 @@
+use napi::bindgen_prelude::*;
+
+#[napi]
+fn get_error() -> Result<()> {
+  Err(Error::new(Status::InvalidArg, "Manual Error".to_owned()))
+}
diff --git a/examples/napi/src/lib.rs b/examples/napi/src/lib.rs
index e982cfba..b688315e 100644
--- a/examples/napi/src/lib.rs
+++ b/examples/napi/src/lib.rs
@@ -5,6 +5,7 @@ mod array;
 mod callback;
 mod class;
 mod r#enum;
+mod error;
 mod nullable;
 mod number;
 mod object;