Gatsby: ValidationError: "siteMetaData" is not allowed

[faizhameed]

I was following this tutorial here
until yesterday it worked. Today when I checked it isn't working
Im getting an error when I try to run gatsby develop

The site's gatsby-config.js failed validation
ValidationError: "siteMetaData" is not allowed
⠋ open and validate gatsby-configs

I tried writing all again but still, it is not working. My gatsby config

module.exports = {
  siteMetaData: {
    title: `Full-Stack Developer`,
    author: `Faiz Hameed`,
  },

  plugins: [`gatsby-plugin-sass`],
}

I am using Ubuntu 18.04.
At first this worked then when i opened the project next day. I tried gatsby develop as the first thing then i got this error

[faizhameed]

changed to siteMetadata instead of siteMetaData