feat: validate app input in createFlow

packages/backend/src/graphql/mutations/create-flow.ts

@@ -1,3 +1,4 @@
+import App from '../../models/app';
 import Step from '../../models/step';
 import Context from '../../types/express/context';
 
@@ -16,15 +17,20 @@ const createFlow = async (
   const connectionId = params?.input?.connectionId;
   const appKey = params?.input?.triggerAppKey;
 
+  await App.findOneByKey(appKey);
+
   const flow = await context.currentUser.$relatedQuery('flows').insert({
     name: 'Name your flow',
   });
 
   if (connectionId) {
-    await context.currentUser
+    const hasConnection = await context.currentUser
       .$relatedQuery('connections')
-      .findById(connectionId)
-      .throwIfNotFound();
+      .findById(connectionId);
+
+    if (!hasConnection) {
+      throw new Error('The connection does not exist!');
+    }
   }
 
   await Step.query().insert({