fix: respected disabled checked

src/elements/radio-button/radio-button-group/radio-button-group.spec.ts

@@ -71,13 +71,13 @@ import '../radio-button-panel.js';
         expect(element.value).to.be.equal(radio.value);
       });
 
-      it('should ignore disabled radios', async () => {
+      it('should respect disabled radio in value getter', async () => {
         const radio = radios[0];
         radio.checked = true;
         radio.disabled = true;
         await waitForLitRender(element);
 
-        expect(element.value).to.be.null;
+        expect(element.value).to.be.equal('Value one');
       });
 
       it('should update disabled on children', async () => {

src/elements/radio-button/radio-button-group/radio-button-group.ts

@@ -59,7 +59,7 @@ class SbbRadioButtonGroupElement extends SbbDisabledMixin(LitElement) {
     if (!this._didLoad) {
       return;
     }
-    if (!val) {
+    if (val == null) {
       this.radioButtons.forEach((r) => (r.checked = false));
       return;
     }
@@ -69,7 +69,7 @@ class SbbRadioButtonGroupElement extends SbbDisabledMixin(LitElement) {
     }
   }
   public get value(): string | null {
-    return this.radioButtons.find((r) => r.checked && !r.disabled)?.value ?? this._fallbackValue;
+    return this.radioButtons.find((r) => r.checked)?.value ?? this._fallbackValue;
   }
   /**
    * Used to preserve the `value` in case the radios are not yet 'loaded'