EC
TS90020
TypeScriptERRORNotableConfigHIGH confidence

Initialize property 'X' in the constructor

Production Risk

Build will fail; resolve before shipping.

What this means

A TypeScript diagnostic (TS90020): Initialize property 'X' in the constructor. This diagnostic is emitted by the TypeScript compiler when initialize property 'X' in the constructor.

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

TypeScript compiler reports TS90020 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS90020
// Initialize property 'X' in the constructor

expected output

error TS90020: Initialize property 'X' in the constructor

Fix

Fix the tsconfig.json option

WHEN When a compiler option is invalid or missing

Fix the tsconfig.json option
// tsconfig.json
{
  "compilerOptions": {
    // Review and correct the flagged option
  }
}
// Run: npx tsc --showConfig to see effective config

Why this works

TypeScript validates tsconfig.json options; check the official tsconfig reference for valid values.

Sources
Official documentation ↗

TypeScript Compiler Diagnostics

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