Fix webhook endpoint validation: unify, harden and reorganize

Author: Dobrunia

src/resolvers/projectNotifications.ts

@@ -127,7 +127,7 @@ async function validateNotificationsRuleChannels(channels: NotificationsChannels
     }
   }
 
-  if (channels.webhook?.isEnabled) {
+  if (channels.webhook?.isEnabled && channels.webhook.endpoint) {
     const webhookError = await validateWebhookEndpoint(channels.webhook.endpoint);
 
     if (webhookError !== null) {

src/resolvers/userNotifications.ts

@@ -47,7 +47,7 @@ export default {
       { input }: ChangeUserNotificationsChannelPayload,
       { user, factories }: ResolverContextWithUser
     ): Promise<ChangeNotificationsResponse> {
-      if (input.webhook?.isEnabled) {
+      if (input.webhook?.isEnabled && input.webhook.endpoint) {
         const webhookError = await validateWebhookEndpoint(input.webhook.endpoint);
 
         if (webhookError !== null) {