Usage with Gatsby V5 breaks Gatsby's Head API

[dev-searchengineunity]

Expected output
Head API to function as described by Gatsby.

Actual output
Adding the gatsby-theme-material-ui to the plugin list in gatsby-config.js resulted in a run time error 'Head is not defined'.

Dependencies in the project with error

  "dependencies": {
    "@emotion/react": "^11.10.5",
    "@emotion/styled": "^11.10.5",
    "@mui/icons-material": "^5.11.0",
    "@mui/material": "^5.11.8",
    "@mui/styles": "^5.11.9",
    "@mui/utils": "^5.11.7",
    "@portabletext/react": "^2.0.1",
    "dotenv": "^16.0.3",
    "gatsby": "^5.5.0",
    "gatsby-plugin-emotion": "^8.5.0",
    "gatsby-plugin-google-analytics": "^5.5.0",
    "gatsby-plugin-google-tagmanager": "^5.5.0",
    "gatsby-plugin-image": "^3.5.0",
    "gatsby-plugin-manifest": "^5.5.0",
    "gatsby-plugin-netlify": "^5.1.0",
    "gatsby-plugin-robots-txt": "^1.8.0",
    "gatsby-plugin-sharp": "^5.5.0",
    "gatsby-plugin-sitemap": "^6.5.0",
    "gatsby-source-filesystem": "^5.5.0",
    "gatsby-source-sanity": "^7.6.2",
    "gatsby-theme-material-ui": "^5.3.0",
    "gatsby-theme-material-ui-top-layout": "^5.2.0",
    "gatsby-transformer-sharp": "^5.5.0",
    "react": "^18.2.0",
    "react-copy-to-clipboard": "^5.1.0",
    "react-dom": "^18.2.0",
    "react-player": "^2.11.0",
    "react-redux": "^8.0.5",
    "redux": "^4.2.1",
    "tss-react": "^4.6.0"
  }

[eddiewilson]

@dev-searchengineunity Are your Gatsby page/template complements you’re exporting the head function .jsx files or .js?

[dev-searchengineunity]

@eddiewilson .js. Oh, does it only work if it is a .jsx?