EC
TS1162
TypeScriptERRORNotableSyntaxHIGH confidence

An object member cannot be declared optional.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1162): An object member cannot be declared optional.. This diagnostic is emitted by the TypeScript compiler when an object member cannot be declared optional..

Why it happens
  1. 1Incorrect TypeScript syntax or type usage
  2. 2Type mismatch between declared and actual value
How to reproduce

TypeScript compiler reports TS1162 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1162
// An object member cannot be declared optional.

expected output

error TS1162: An object member cannot be declared optional.

Fix

Address the TypeScript diagnostic

WHEN When this error is reported by the compiler

Address the TypeScript diagnostic
// Run the TypeScript compiler for details:
npx tsc --noEmit
// Use the TypeScript playground to test your code:
// https://www.typescriptlang.org/play

Why this works

Review the full error message and location; the TypeScript handbook provides guidance on each error category.

Sources
Official documentation ↗

TypeScript Compiler Diagnostics

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