Fix getter

src/components/radio-group/radio-group.ts

@@ -24,6 +24,14 @@ export default class SlRadioGroup extends LitElement {
   /** The radio group label. Required for proper accessibility. Alternatively, you can use the label slot. */
   @property() label = '';
 
+  /** The current value of the radio group. */
+  @property()
+  get value() {
+    if (!this._value) return this.getCurrentValue();
+
+    return this._value;
+  }
+
   set value(newValue) {
     const index = this.getAllRadios().findIndex(el => el.value === newValue);
     const oldValue = this._value;
@@ -38,12 +46,6 @@ export default class SlRadioGroup extends LitElement {
     }
   }
 
-  /** The current value of the radio group. */
-  @property()
-  get value() {
-    return this._value;
-  }
-
   /** Shows the fieldset and legend that surrounds the radio group. */
   @property({ type: Boolean, attribute: 'fieldset' }) fieldset = false;
 
@@ -66,6 +68,12 @@ export default class SlRadioGroup extends LitElement {
     });
   }
 
+  getCurrentValue() {
+    const valRadio = this.getAllRadios().filter(el => el.checked);
+    this._value = valRadio.length === 1 ? valRadio[0].value : '';
+    return this._value;
+  }
+
   handleFocusIn() {
     // When tabbing into the fieldset, make sure it lands on the checked radio
     requestAnimationFrame(() => {