Clear wizard interceptor on wizard start and close

Without doing this, an interceptor from a different wizard can run
when a new wizard is opened causing incorrect validation.

src/lib/stores/wizard.ts

@@ -24,6 +24,7 @@ function createWizardStore() {
             update((n) => {
                 n.show = true;
                 n.component = component;
+                n.interceptor = null;
                 n.media = media;
                 trackEvent('wizard_start');
                 return n;
@@ -39,6 +40,7 @@ function createWizardStore() {
             update((n) => {
                 n.show = false;
                 n.component = null;
+                n.interceptor = null;
                 n.media = null;
 
                 return n;