Is it permissible for someone who is certain of the Imam's clear grammatical error (lahn jali) in recitation to leave the prayer?

If the melodic error (laḥn) in Al-Fatiḥah alters the meaning, the congregant (ma'mūm) should correct the Imam if possible. Otherwise, he should separate from the Imam by intention (niyyah) and complete his prayer individually, without breaking it. However, if the melodic error is in other than Al-Fatiḥah, it is not prescribed to separate from the Imam for that reason.