Fix form reset for x-model radio inputs

packages/alpinejs/src/directives/x-model.js

@@ -91,7 +91,7 @@ directive('model', (el, { modifiers, expression }, { effect, cleanup }) => {
     // on nextTick so the page doesn't end up out of sync
     if (el.form) {
         let removeResetListener = on(el.form, 'reset', [], (e) => {
-            nextTick(() => el._x_model && el._x_model.set(el.value))
+            nextTick(() => el._x_model && (el.type !== 'radio' || el.checked) && el._x_model.set(el.value))
         })
         cleanup(() => removeResetListener())
     }

tests/cypress/integration/directives/x-model.spec.js

@@ -210,6 +210,28 @@ test('x-model updates value when the form is reset',
     }
 )
 
+test(
+    "x-model radio updates value when the form is reset",
+    html`
+    <div x-data="{ foo: undefined }">
+        <form>
+            <input type="radio" value="radio1" x-model.fill="foo"></input>
+            <input type="radio" value="radio2" x-model.fill="foo" checked></input>
+            <input type="radio" value="radio3" x-model.fill="foo"></input>
+            <button type="reset">Reset</button>
+        </form>
+        <span x-text="foo"></span>
+    </div>
+    `,
+    ({ get }) => {
+        get("span").should(haveText("radio2"));
+        get("input[value='radio1']").click();
+        get("span").should(haveText("radio1"));
+        get("button").click();
+        get("span").should(haveText("radio2"));
+    }
+);
+
 test('x-model with fill modifier takes input value on null, empty string or undefined',
     html`
     <div x-data="{ a: 123, b: 0, c: '', d: null, e: {} }">