ts-r
  • Error
  • Reported by the type checker

TS1196

Catch clause variable type annotation must be 'any' or 'unknown' if specified.

A `catch` variable is annotated with a type other than `any` or `unknown`. Remove the annotation or use `unknown` and narrow it.

What it means

Anything can be thrown in JavaScript, so a catch clause can't promise a specific type for the caught value. Only any and unknown are allowed as annotations.

Example

index.ts
try {
  JSON.parse('{');
} catch (e: Error) {
  console.log(e);
}
export {};
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(3,13): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.

Recorded by node scripts/verify-examples.mjs with ts-r built from commit 6deaf01. The example uses the default tsconfig: strict, target: es2022, module: esnext, moduleResolution: bundler.

How to fix

  • Annotate with unknown (or leave it out) and narrow: if (e instanceof Error) { ... }.