EC
TS2863
TypeScriptERRORNotableTypeHIGH confidence

A class cannot extend a primitive type like 'X'. Classes can only extend cons...

Production Risk

Build will fail; resolve before shipping.

What this means

A type-checking error (TS2863): A class cannot extend a primitive type like 'X'. Classes can only extend constructable values.. This diagnostic is emitted by the TypeScript compiler when a class cannot extend a primitive type like 'X'. Classes can only extend constructable values..

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

TypeScript compiler reports TS2863 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS2863
// A class cannot extend a primitive type like 'X'. Classes can only extend constructable values.

expected output

error TS2863: A class cannot extend a primitive type like 'X'. Classes can only extend constructable values.

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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