josdejong/mathjs

null/undefined treated as valid only for left side of comparison operators

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#1,391 opened on Jan 31, 2019

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 (11 comments) (0 reactions) (0 assignees)JavaScript (13,832 stars) (1,298 forks)batch import
bughelp wanted

Description

Using mathjs@5.4.1

When the null value is on the right side, the correct error is thrown (actual: null):

> require('mathjs').eval('1 > null')
TypeError: Unexpected type of argument in function larger (expected: number or Array or DenseMatrix or SparseMatrix or string or boolean or Matrix or BigNumber or Complex or Fraction, actual: null, index: 1)

However, when the null value is on the left side, the error mistakenly identifies the right side as the source of the problem (actual: number):

> require('mathjs').eval('null > 1')
TypeError: Unexpected type of argument in function larger (expected: Array or DenseMatrix or SparseMatrix or Matrix, actual: number, index: 1)

Contributor guide

Tech stack
javascript
Domain
tooling
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
JavaScriptfamiliarity with mathjs error handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85
Research direction
Investigate the comparison operator functions in mathjs, specifically the error handling when left and right operands are of different types. The issue reports that null on the left side causes an incorrect error message indicating the right side is wrong. Look at the function 'larger' and similar comparison functions to see how they validate types and generate error messages. The fix likely involves ensuring that both arguments are checked symmetrically.