TS1248

A class member cannot have the 'const' keyword.

Broken Code ❌

class MyBaseClass {}
 
export class MyExtendedClass extends MyBaseClass {
  myConstant = '';
}

Fixed Code ✔️

When inheriting from a base class, you have to use modifiers like readonly if you want your class members to become constant:

class MyBaseClass {}
 
export class MyExtendedClass extends MyBaseClass {
  readonly myConstant = '';
}