requireNonException

function requireNonException<T>(
  value: T | Exception,
  message: string = "Expected a value that is not an Exception."
): T;

The library's own hierarchy only. A plain Error does not qualify, which is exactly what makes the check useful in a catch block that has to tell the two apart.

isX and nonX answer a question and never interrupt control flow; requireX and requireNonX hand the value back or throw. The scheme is explained in Validation conventions.

Parameters

Parameter	Type	Description
`value`	`T \\| Exception`	The value to validate.
`message` (optional) `= "Expected a value that is not an Exception."`	`string`	The message of the exception. A default is used when omitted.

Returns

T — the same value, with an Exception excluded from its type.

Throws

Exception	Condition
`IllegalArgumentException`	the value is an `Exception`.

Examples

What passes and what does not

requireNonException(new Error()); // => new Error()
requireNonException({}); // => {}
requireNonException(new IllegalArgumentException()); // throws IllegalArgumentException

Source

src/lang/base/requireNonException.ts

23 September 2026

This documentation was generated with AI (Claude) from the library's source code.

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