TS1280

Namespaces are not allowed in global script files when verbatimModuleSyntax is enabled. If this file is not intended to be a global script, set moduleDetection to force or add an empty export {} statement.

Broken Code ❌

module global {
  namespace globalThis {
    var signin: () => string[];
  }
}
 
this.signin();

Fixed Code ✔️

Use a quotes around the name global and turn it into an ambient module by using the declare module syntax:

declare module 'global' {
  namespace globalThis {
    var signin: () => string[];
  }
}
 
this.signin();