Next.js 8 released
Ever since the first release of Next.js the page script tag was part of the initial html, meaning it was loaded even though it wouldn’t be used if there were no runtime errors. When starting the Next.js development server, it has to run some initial compilation to be able to serve requests, by default, Next.js would wait for this compilation step to finish before starting the HTTP server, meaning that if you ran and then went to your browser it could sometimes happen that you’d get a “This site can’t be reached” message because the HTTP server was not listening for connections yet. Next.js exposes a built-in component to introduce changes to the :
The component can even be used multiple times in different components, for example your layout component could set some default head tags.
Source: nextjs.org