tests/cases/compiler/constWithNonNull.ts(4,1): error TS2540: Cannot assign to 'x' because it is a constant or a read-only property.


==== tests/cases/compiler/constWithNonNull.ts (1 errors) ====
    // Fixes #21848
    
    declare const x: number | undefined;
    x!++;
    ~
!!! error TS2540: Cannot assign to 'x' because it is a constant or a read-only property.
    