Community Wishlist Survey 2019/Archive/Stack trace of errors (error handling) by parser functions

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Stack trace of errors (error handling) by parser functions

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• Problem: When parser function (ex. expr) gets invalid input, it generates error message which sometimes isn't helpful:

({{#expr:<span class="error">Error of the Template</span>}}), especially when editing templates which calls other templates (ex. Inflation) and use #iferror with custom error messages (or with incorrect pairs of brackets {}).

• Who would benefit: Wikipedia editors, Wikipedia template editors
• Proposed solution: Chain (stack trace) errors (or invalid input):

: ({{#expr:<span class="error">Error of the Template</span>}}: <span class="error">Error of the Template</span>) on article page, or only in preview

• More comments:

• Phabricator tickets:

• Proposer: 89.25.210.104 18:46, 30 October 2018 (UTC)