TS1038
TypeScriptERRORNotableSyntaxHIGH confidence

A 'declare' modifier cannot be used in an already ambient context.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1038): A 'declare' modifier cannot be used in an already ambient context.. This diagnostic is emitted by the TypeScript compiler when a 'declare' modifier cannot be used in an already ambient context..

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

TypeScript compiler reports TS1038 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1038
// A 'declare' modifier cannot be used in an already ambient context.

expected output

error TS1038: A 'declare' modifier cannot be used in an already ambient context.

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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