Fix export service error with the new timetable config schema

[zehata]

Updated the validation logic in the export service

Context

Resolves https://t.me/NUSMods/13264
This was caused by the validation logic in

nusmods/export/src/data.ts

Lines 64 to 71 in f722758

	const timetableSchema = Joi.object().pattern(
	Joi.string(),
	Joi.object().pattern(Joi.string(), Joi.string()),
	);
	const taModulesConfigSchema = Joi.object().pattern(
	Joi.string(),
	Joi.array().items(Joi.array().length(2).ordered(Joi.string(), Joi.string())),
	);

not updated for the updated in timetable config schema.

The systemic problem is that there is currently no test coverage for the export service. It also took a long time to fix because the readme is really outdated.

Other Information

Sample image and pdf output of the export service, showing no regression from before #4225:
My Timetable.pdf

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.78%. Comparing base (988c6fd) to head (e28833b).
⚠️ Report is 157 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4277      +/-   ##
==========================================
+ Coverage   54.52%   56.78%   +2.26%     
==========================================
  Files         274      297      +23     
  Lines        6076     6924     +848     
  Branches     1455     1671     +216     
==========================================
+ Hits         3313     3932     +619     
- Misses       2763     2992     +229     

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Project	Deployment	Review	Updated (UTC)
nusmods-export	Ready	Preview, Comment	Jan 1, 2026 6:29am
nusmods-website	Ready	Preview, Comment	Jan 1, 2026 6:29am

[leslieyip02]

Yeah the export service is quite old and the testing issue was raised in #3926. We should probably do something about it.

[leslieyip02]

LGTM

[leslieyip02]

For future reference, we missed 3 issues:

1. .positive() expects a lesson index greater than 0, so it flags lesson indices of 0 as invalid
2. .ordered() will restrict the lesson indices array's length, so we should use .items() instead
3. Default value of the ta key in the export state should be [] instead of {}

Fixed by these commits: (this is pretty sloppy but I just wanted to get it fixed)

• e58d5c5
• 0eef0ba
• 1091598
• 9c69174