EC
TS6909
TypeScriptERRORNotableConfigHIGH confidence

`true` if `composite`, `false` otherwise

Production Risk

Build will fail; resolve before shipping.

What this means

A compiler configuration error (TS6909): `true` if `composite`, `false` otherwise. This diagnostic is emitted by the TypeScript compiler when `true` if `composite`, `false` otherwise.

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

TypeScript compiler reports TS6909 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS6909
// `true` if `composite`, `false` otherwise

expected output

error TS6909: `true` if `composite`, `false` otherwise

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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