oxc-project/oxc · warning · OxcDiagnostic

Error message should not be an empty string.

Error message

Error message should not be an empty string.

What it means

Diagnostic from oxlint's `unicorn/error-message` rule. The message argument exists but is an empty string: either a `''`/`""` string literal or an empty template literal (span of exactly two backtick characters). An empty message gives consumers of the error no information, so the rule asks for a non-empty string describing what went wrong.

Source

Thrown at crates/oxc_linter/src/rules/unicorn/error_message.rs:21

    ast::{Argument, CallExpression, Expression, NewExpression},
};
use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_semantic::IsGlobalReference;
use oxc_span::Span;

use crate::{AstNode, context::LintContext, rule::Rule, utils::BUILT_IN_ERRORS};

fn missing_message(ctor_name: &str, span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn(format!("Pass a message to the {ctor_name:1} constructor."))
        .with_help(
            "A descriptive message makes the error easier to debug when it is caught or logged.",
        )
        .with_label(span)
}

fn empty_message(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Error message should not be an empty string.")
        .with_help("Provide a non-empty string that describes what went wrong.")
        .with_label(span)
}

fn not_string(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Error message should be a string.")
        .with_help(
            "The first argument to an error constructor should be a string describing the error.",
        )
        .with_label(span)
}

#[derive(Default, Debug, Clone)]
pub struct ErrorMessage;

declare_oxc_lint!(
    /// ### What it does
    ///

View on GitHub (pinned to e1e7af627c)

Solutions

1. Write a one-line description of the failure in the string.
2. If the message is built dynamically, guard it so it is never empty when thrown.
3. Add a lint step (`oxlint` with unicorn) to CI so placeholder errors are caught before merge.

Example fix

// before
throw new Error('');
// after
throw new Error('Failed to load configuration');

When it happens

Trigger: `throw new Error('')` or `` throw new Error(``) `` — the argument at the message position is a string literal with empty value. Only literals are checked; an empty-but-computed expression like `new Error(msg)` is not flagged.

Common situations: Placeholder errors written during development and never filled in; refactors that removed the message text but left the quotes; generated code that defaults messages to empty strings.

Related errors

• Pass a message to the {ctor_name:1} constructor.
• Invalid class name, use `{expected}`.
• Missing call to `super()` in constructor.
• The `name` property should be set to `{name}`.
• Error message should be a string.

AI-assisted analysis of oxc-project/oxc@e1e7af627c (2026-08-20). Data as JSON: /api/errors/8e9f1726d290188a. Report an issue: GitHub.