diff --git a/examples/project-structure/src/api.v b/examples/project-structure/src/api.v
index 48fbfa9..79a4f8f 100644
--- a/examples/project-structure/src/api.v
+++ b/examples/project-structure/src/api.v
@@ -5,7 +5,7 @@ fn (mut app App) bind(w &Webview) {
 	// The first string argument is the functions name in the JS frontend.
 	// Use JS's `camelCase` convention or distinct identifiers if you prefer it.
 	w.bind('get_settings', app.get_settings)
-	w.bind_ctx('toggle_setting', toggle, app) // Alternatively use the ctx ptr to pass a struct.
+	w.bind_with_ctx('toggle_setting', toggle, app) // Alternatively use the ctx ptr to pass a struct.
 	w.bind('login', login)
 	w.bind('fetch_news', fetch_news)
 }
@@ -17,7 +17,7 @@ fn (app App) get_settings(_ &Event) Settings {
 }
 
 // Returns a value when it's called from JS.
-// This examples uses bind_ctx, adding the App struct as context argument.
+// This examples uses `bind_with_ctx` to add the App struct as context argument.
 fn toggle(_ &Event, mut app App) bool {
 	app.settings.toggle = !app.settings.toggle
 	dump(app.settings.toggle)
diff --git a/examples/v-js-interop-app/main.v b/examples/v-js-interop-app/main.v
index 555342c..70a6f80 100644
--- a/examples/v-js-interop-app/main.v
+++ b/examples/v-js-interop-app/main.v
@@ -26,7 +26,7 @@ fn (app App) get_settings(_ &Event) Settings {
 }
 
 // Returns a value when it's called from JS.
-// This examples uses bind_ctx, adding the App struct as context argument.
+// This examples uses `bind_with_ctx` to add the App struct as context argument.
 fn toggle(_ &Event, mut app App) bool {
 	app.settings.toggle = !app.settings.toggle
 	dump(app.settings.toggle)
@@ -78,7 +78,7 @@ fn main() {
 	// The first string argument is the functions name in the JS frontend.
 	// Use JS's `camelCase` convention or distinct identifiers if you prefer it.
 	w.bind('get_settings', app.get_settings)
-	w.bind_ctx('toggle_setting', toggle, &app) // Alternatively use the ctx ptr to pass a struct.
+	w.bind_with_ctx('toggle_setting', toggle, &app) // Alternatively use the ctx ptr to pass a struct.
 	w.bind('login', login)
 	w.bind('fetch_news', fetch_news)
 
diff --git a/src/lib.v b/src/lib.v
index 0bcbd89..6b38d77 100644
--- a/src/lib.v
+++ b/src/lib.v
@@ -31,16 +31,6 @@ pub struct CreateOptions {
 	window voidptr
 }
 
-[params]
-pub struct ReturnParams {
-	kind ReturnKind
-}
-
-pub enum ReturnKind {
-	value
-	error
-}
-
 // A Hint that is passed to the Webview 'set_size' method to determine the window sizing behavior.
 pub enum Hint {
 	// Width and height are default size.
@@ -150,28 +140,71 @@ pub fn (w &Webview) eval(code string) {
 	C.webview_eval(w, &char(code.str))
 }
 
-// bind binds a callback so that it will appear under the given name as a
-// global JavaScript function. Internally it uses webview_init().
-// The callback receives an `&Event` pointer.
+// bind binds a V callback to a global JavaScript function that will appear under the given name.
+// The callback receives an `&Event` argument. Internally it uses webview_init().
 pub fn (w &Webview) bind[T](name string, func fn (&Event) T) {
 	C.webview_bind(w, &char(name.str), fn [w, func] [T](event_id &char, args &char, ctx voidptr) {
 		e := unsafe { &Event{w, event_id, args} }
 		spawn fn [func] [T](e &Event) {
 			result := func(e)
-			e.@return(result)
+			e.@return(result, .value)
+		}(e.async())
+	}, 0)
+}
+
+// bind_opt binds a V callback with a result return type to a global JavaScript function that will
+// appear under the given name. The callback receives an `&Event` argument. The callback can return an
+// error to the calling JavaScript function. Internally it uses webview_init().
+pub fn (w &Webview) bind_opt[T](name string, func fn (&Event) !T) {
+	C.webview_bind(w, &char(name.str), fn [w, func] [T](event_id &char, args &char, ctx voidptr) {
+		e := unsafe { &Event{w, event_id, args} }
+		spawn fn [func] [T](e &Event) {
+			if result := func(e) {
+				e.@return(result, .value)
+			} else {
+				e.@return(err.str(), .error)
+			}
 		}(e.async())
 	}, 0)
 }
 
-// bind_ctx binds a callback so that it will appear under the given name as a
-// global JavaScript function. Internally it uses webview_init().
-// The callback receives an `7Event` pointer and a user-provided ctx pointer.
+// bind_ctx binds a V callback to a global JavaScript function that will appear under the given name.
+// The callback receives an `&Event` and a user-provided ctx pointer argument.
+[deprecated: 'will be removed with v0.7; use `bind_with_ctx` instead.']
 pub fn (w &Webview) bind_ctx[T](name string, func fn (e &Event, ctx voidptr) T, ctx voidptr) {
 	C.webview_bind(w, &char(name.str), fn [w, func] [T](event_id &char, args &char, ctx voidptr) {
 		e := unsafe { &Event{w, event_id, args} }
 		spawn fn [func, ctx] [T](e &Event) {
 			result := func(e, ctx)
-			e.@return(result)
+			e.@return(result, .value)
+		}(e.async())
+	}, ctx)
+}
+
+// bind_with_ctx binds a V callback to a global JavaScript function that will appear under the given name.
+// The callback receives an `&Event` and a user-provided ctx pointer argument.
+pub fn (w &Webview) bind_with_ctx[T](name string, func fn (e &Event, ctx voidptr) T, ctx voidptr) {
+	C.webview_bind(w, &char(name.str), fn [w, func] [T](event_id &char, args &char, ctx voidptr) {
+		e := unsafe { &Event{w, event_id, args} }
+		spawn fn [func, ctx] [T](e &Event) {
+			result := func(e, ctx)
+			e.@return(result, .value)
+		}(e.async())
+	}, ctx)
+}
+
+// bind_opt_with_ctx binds a V callback with a result return type to a global JavaScript function that will
+// appear under the given name. The callback receives an `&Event` and a user-provided ctx pointer argument.
+// The callback can return an error to the calling JavaScript function. Internally it uses webview_init().
+pub fn (w &Webview) bind_opt_with_ctx[T](name string, func fn (e &Event, ctx voidptr) T, ctx voidptr) {
+	C.webview_bind(w, &char(name.str), fn [w, func] [T](event_id &char, args &char, ctx voidptr) {
+		e := unsafe { &Event{w, event_id, args} }
+		spawn fn [func, ctx] [T](e &Event) {
+			if result := func(e, ctx) {
+				e.@return(result, .value)
+			} else {
+				e.@return(err, .error)
+			}
 		}(e.async())
 	}, ctx)
 }
@@ -250,7 +283,7 @@ pub fn (e &Event) int_opt(idx usize) ?int {
 	return e.args_json[int]() or { return none }[int(idx)] or { return none }
 }
 
-// bool_opt decodes and return the argument with the given index as boolean option.
+// bool_opt parses and return the argument with the given index as boolean option.
 [deprecated: 'will be removed with v0.7; use `get_arg[T](idx int) !T` instead. E.g: `e.get_arg[bool](0)!`']
 pub fn (e &Event) bool_opt(idx usize) ?bool {
 	return e.args_json[bool]() or { return none }[int(idx)] or { return none }
diff --git a/src/utils.v b/src/utils.v
index 96d31e7..4263e31 100644
--- a/src/utils.v
+++ b/src/utils.v
@@ -2,8 +2,13 @@ module webview
 
 import json
 
+enum ReturnKind {
+	value
+	error
+}
+
 // copy_char copies a C style string. The functions main use case is passing an `event_id &char`
-// to another thread. It helps to keep the event id available when executing `@return`
+// to another thread. It helps to keep the event id available when executing `@retrun`
 // from the spawned thread. Without copying the `event_id` might get obscured during garbage
 // collection and returning data to a calling JS function becomes error prone.
 fn copy_char(s &char) &char {
@@ -14,11 +19,11 @@ fn copy_char(s &char) &char {
 // be provided to allow the internal RPC engine to match the request and response.
 // If the status is zero - the result is expected to be a valid JSON value.
 // If the status is not zero - the result is an error JSON object.
-fn (e &Event) @return[T](result T, return_params ReturnParams) {
+fn (e &Event) @return[T](result T, kind ReturnKind) {
 	$if result is voidptr {
-		C.webview_return(e.instance, e.event_id, 0, &char(''.str))
+		C.webview_return(e.instance, e.event_id, int(kind), &char(''.str))
 	} $else {
-		C.webview_return(e.instance, e.event_id, 0, &char(json.encode(result).str))
+		C.webview_return(e.instance, e.event_id, int(kind), &char(json.encode(result).str))
 	}
 }
 
diff --git a/tests/v_fn_call_test.v b/tests/v_fn_call_test.v
index 60d76ec..a15480a 100644
--- a/tests/v_fn_call_test.v
+++ b/tests/v_fn_call_test.v
@@ -1,5 +1,6 @@
 import webview
 import time
+import os
 
 struct Person {
 	name string
@@ -149,3 +150,41 @@ fn test_return_value_from_threaded_task_to_js() {
 	w.set_html(gen_html(@FN, script))
 	w.run()
 }
+
+fn test_fn_call_with_error() {
+	w := webview.create(debug: true)
+	w.set_size(600, 400, .@none)
+	w.bind_opt('v_fn_with_custom_error', fn (e &webview.Event) !int {
+		return error('my error')
+	})
+	w.bind[voidptr]('assert_custom_error', fn (e &webview.Event) {
+		assert e.get_arg[string](0) or { '' } == 'my error'
+	})
+	w.bind_opt('v_fn_with_error_propagation', fn (e &webview.Event) !string {
+		return os.existing_path('my_inexistent_path/file.v')!
+	})
+	w.bind[voidptr]('assert_error_propagation', fn (e &webview.Event) {
+		assert e.get_arg[string](0) or { '' } == 'path does not exist'
+	})
+	w.bind[voidptr]('exit', fn [w] (_ &webview.Event) {
+		w.terminate()
+	})
+	script := '
+	setTimeout(async () => {
+		try {
+			await window.v_fn_with_custom_error();
+		} catch (err) {
+			console.log(err);
+			await window.assert_custom_error(err);
+		}
+		try {
+			await window.v_fn_with_error_propagation();
+		} catch (err) {
+			console.log(err);
+			await window.assert_error_propagation(err);
+			await window.exit();
+		}
+	}, 500)'
+	w.set_html(gen_html(@FN, script))
+	w.run()
+}