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Rslint

    use-unknown-in-catch-callback-variable

    Configuration

    rslint.config.ts
    import { defineConfig, ts } from '@rslint/core';

export default defineConfig([
  ts.configs.recommended,
  {
    rules: {
      '@typescript-eslint/use-unknown-in-catch-callback-variable': 'error',
    },
  },
]);

    Rule Details

    Enforce typing the rejection callback parameter of .catch() and .then() as unknown. Similar to how catch clause variables should be typed as unknown (since any value can be thrown), Promise rejection callback parameters should also be typed as unknown. This prevents unsafe property accesses and assumptions about the shape of the rejection reason.

    The rule checks .catch(callback) and .then(onFulfilled, onRejected) calls on thenable types and flags the rejection callback parameter when it is not typed as unknown.

    Examples of incorrect code for this rule:

    promise.catch(err => {});
promise.catch((err: Error) => {});
promise.then(undefined, err => {});
promise.then(undefined, (err: string) => {});

    Examples of correct code for this rule:

    promise.catch((err: unknown) => {});
promise.then(undefined, (err: unknown) => {});
promise.catch((...args: [unknown]) => {});

    Original Documentation