# E0240: '!' is not allowed on methods

In TypeScript, `!` after a field name indicates a definite assignment assertion. Because `!` only applies to fields, is a syntax error to write `!` after a method name:

    class Banana {
      skin!: BananaSkin | undefined;

      peel!() {
        this.skin = undefined;
      }
    }

To fix this error, remove the `!`:

    class Banana {
      skin!: BananaSkin | undefined;

      peel() {
        this.skin = undefined;
      }
    }

Introduced in quick-lint-js version 2.6.0.

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