better config/CLI args validation

Description

karma start test/e2e/basic/karma.conf.js --log-level

/Users/vojta/Code/karma/node_modules/log4js/lib/logger.js:56
    return this.level.isLessThanOrEqualTo(otherLevel);
                      ^
TypeError: Cannot call method 'isLessThanOrEqualTo' of undefined
    at Logger.isLevelEnabled (/Users/vojta/Code/karma/node_modules/log4js/lib/logger.js:56:23)
    at Logger.(anonymous function) [as debug] (/Users/vojta/Code/karma/node_modules/log4js/lib/logger.js:67:22)
    at requirePlugin (/Users/vojta/Code/karma/lib/plugin.js:12:9)
    at /Users/vojta/Code/karma/lib/plugin.js:38:9
    at Array.forEach (native)
    at Object.exports.resolve (/Users/vojta/Code/karma/lib/plugin.js:25:11)
    at Object.exports.start (/Users/vojta/Code/karma/lib/server.js:254:35)
    at Object.<anonymous> (/Users/vojta/Code/karma/bin/karma:20:39)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:901:3

Contributor guide

Tech stack

javascriptnodejs

Domain

clitooling

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

2

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

Basic Node.jsFamiliarity with CLI toolsUnderstanding of argument parsing

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

75

Research direction

Examine the CLI entry point in bin/karma to understand how arguments are parsed. The error trace shows the crash in plugin.js, but the root cause is missing validation for log level value. Look for existing tests in test/ directory related to CLI. A fix could involve adding a check that a value is provided for log level, possibly using a library like minimist or yargs. Write a test to cover the case of missing argument value.