EC
TS5063
TypeScriptERRORNotableConfigHIGH confidence

Substitutions for pattern 'X' should be an array.

Production Risk

Build will fail; resolve before shipping.

What this means

A compiler configuration error (TS5063): Substitutions for pattern 'X' should be an array.. This diagnostic is emitted by the TypeScript compiler when substitutions for pattern 'X' should be an array..

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

TypeScript compiler reports TS5063 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS5063
// Substitutions for pattern 'X' should be an array.

expected output

error TS5063: Substitutions for pattern 'X' should be an array.

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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