@antithrow/no-unused-result

Rule id: @antithrow/no-unused-result

Reports expression statements whose value is a Result — the analog of no-unused-expressions for typed errors. A Result that is never inspected is a silently-dropped error.

Applies to values whose type includes Ok<T, E>, Err<T, E>, or Pending<T, E> from the root antithrow entrypoint. Values from the legacy antithrow/legacy entrypoint are ignored.

Metadata

Field	Value
Type	problem
Recommended	error
Requires type information	yes
Fixable	no
Has suggestions	yes

Options

None.

{ "@antithrow/no-unused-result": "error" }

Message IDs

ID	Template
unusedResult	This Result must be used. Handle the error case or explicitly discard it with \void`.`
addVoid	Explicitly discard the Result with \void`.`

Detection

The rule walks through expression wrappers so that Result types embedded inside these shapes are still caught:

• cond ? a : b (checks both branches)
• a && b, a || b, a ?? b (checks both operands)
• (a, b, c) (checks each expression)
• expr as T, expr! (unwraps before checking)
• obj?.prop (unwraps ChainExpression)

void expr silences the rule — that is the explicit-discard escape hatch.

Suggestion

A single suggestion is offered: prepend void to the expression (wrapping in parentheses if the expression's precedence requires it). The suggestion is not applied automatically; the author should prefer handling the branch.

Example

// reports:
readFile("/etc/hostname");

// ok (explicit discard):
void readFile("/etc/hostname");

// ok (handled):
const contents = await readFile("/etc/hostname");
if (contents.isOk()) {
	process.stdout.write(contents.value);
}