TS1229
TypeScriptERRORNotableSyntaxHIGH confidence
A type predicate cannot reference a rest parameter.
Production Risk
Build will fail; resolve before shipping.
What this means
A syntax error (TS1229): A type predicate cannot reference a rest parameter.. This diagnostic is emitted by the TypeScript compiler when a type predicate cannot reference a rest parameter..
Why it happens
- 1Incorrect TypeScript syntax or type usage
- 2Type mismatch between declared and actual value
How to reproduce
TypeScript compiler reports TS1229 during type checking.
trigger — this will error
trigger — this will error
// Triggers TS1229 // A type predicate cannot reference a rest parameter.
expected output
error TS1229: A type predicate cannot reference a rest parameter.
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
Content generated with AI assistance and reviewed for accuracy. Found an error? hello@errcodes.dev