EC
TS1504
TypeScriptERRORNotableSyntaxHIGH confidence

Subpattern flags must be present when there is a minus sign.

Production Risk

Build will fail; resolve before shipping.

What this means

A syntax error (TS1504): Subpattern flags must be present when there is a minus sign.. This diagnostic is emitted by the TypeScript compiler when subpattern flags must be present when there is a minus sign..

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

TypeScript compiler reports TS1504 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS1504
// Subpattern flags must be present when there is a minus sign.

expected output

error TS1504: Subpattern flags must be present when there is a minus sign.

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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