servo/servo

Provide actual messages in JS errors

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#40756 opened on Nov 20, 2025

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 (4 comments) (0 reactions) (0 assignees)Rust (36,724 stars) (3,630 forks)batch import
good first issue

Description

Now that each error variant accepts Option<String> (#39053), we should start to write actually error messages instead of passing None.

OFF-TOPIC: Should we accept Cow rather than string? Or maybe even create JSString directly? (probably not).

Contributor guide

Tech stack
rust
Domain
backenddeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
RustServo error handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
Start by reviewing the previous PR #39053 that added Option<String> to error variants. Then, search for instances where None is passed as the error message and replace them with appropriate string messages. Consider checking comments on this issue for any specific guidance on error message format. Look at existing error messages in similar files for consistency.