Error: Asset 'webhooks/ActionsOnGoogleFulfillment' cannot be deployed - google-cloud-platform

Question

I wanted to build a Google assistant with custom actions using actions-sdk. Since I am new to this, I have followed the steps in the tutorial "Build Actions for Google Assistant using Actions SDK (Level 1)" as it is, inorder to build a sample assistant. I followed the tutorial as it is. However, in step 5(Implement fulfillment), when trying to test the the fulfillment by running the command
gactions deploy preview
I am getting the below output in the terminal with error
Sending configuration files...
Sending resources...
Waiting for server to respond. It could take up to 1 minute if your cloud function needs to be redeployed.
[ERROR] Server did not return HTTP 200.
{
"error": {
"code": 400,
"message": "Asset 'webhooks/ActionsOnGoogleFulfillment' cannot be deployed. [An operation on function cf-_CcGD8lKs_F_LHmFYfJZsQ-name in region us-central1 in project <my-project-id> is already in progress. Please try again later.]"
}
}
And when I checked the "Google Cloud Platform -> Cloud Functions Console" for this project, the following is seen.
Image 1(Screenshot)
Cloud Platform Cloud Functions Console
A failed deploy of cloud function with an exclamation mark. And if I delete that functions, then immediately a new function is deployed automatically. But instead of an exclamation mark, a spinning wheel symbol(loading/still deploying) mark is present. I cannot delete that cloud function if it is still loading/deploying. Then after 10-15 min, the spinning symbol changes to exclamation symbol. And then if I delete it, then again a new one automatically appears. And it goes on like this
Image 2 (Screenshot)
Cloud Platform Cloud Function Console
This problem arises only when implementing a webhook/fulfillment(Step 5). For static Actions' response, it successfully deploys for testing on entering the command "gactions deploy preview".(Step 1 to Step 4 are successfully implemented)
I have followed the tutorial as it is, hence the code and directory structure is the same as in tutorial,(only the project-id or actions-console project name will be different).
Github Repository for Code
Since, this is only for the tutorial, at present I am not using a billing account, instead did the following changes in package.json(changed node version from 10 to 8.).
"engines": {
"node": "8"
},
Due to this continuous automatic failed deployment, when I try to explicitly deploy the project, as mentioned above, this error occurs.
"An operation on function cf-_CcGD8lKs_F_LHmFYfJZsQ-name in region us-central1 in project <my-project-id> is already in progress. Please try again later".
Can anyone please suggest how to stop this continuous automatic failed deployment of the cloud functions, so that the function I deploy will be successfully deployed? Would really appreciate your help.
(Note: This is the first time I have posted a question in stack overflow, so please let me know if there are any mistakes or stack overflow question conventions I might not have followed. I will improve it.)

Answer 1

Posting this as Community Wiki as it's based in the comments.
As clarified the issue seems to be the billing account, as the tutorial mentions that it's necessary to have one set for the Cloud Functions to be deployed correctly. Besides that, it's not possible to deploy Cloud Functions (webhooks) without a billing account, so yes, even though that you are not using Node.js 10, you will need to have a billing account configured for your project.
To summarize, billing account will be needed to avoid any possible deployment failure, even if you are not using Node.js 10, as explained in the followed tutorial.