In Singaporean English (Singlish), "shag" does not mean what it typically implies in British or American English. Instead, it is a colloquial term used to express extreme tiredness or exhaustion.

It is believed to be a phonetic corruption of the word "shacked" (as in "shagged out"), but in Singlish, it has completely lost its sexual connotation. For example, a student might say, "After CCAs, I'm so shag," meaning they are very tired from co-curricular activities.

So, in your original sentence, "shagged from her co-curricular activity" likely meant she was exhausted, not involved in any inappropriate act. It’s not a typo, but a correct (though informal) use of Singlish.