The missing slur in FC (→GE) is an oversight of Fontana. The slur of A was being extended so that it could also encompass the last crotchet in b. 12. The added fragment ends already in the next bar, in which, however, there is not a single element of notation to which it could have been led. Therefore, it is simply an inaccuracy, quite frequent for Chopin.
Compare the passage in the sources »
category imprint: Differences between sources; Source & stylistic information
issues: Inaccurate slurs in A, Corrections in A, Embracing slurs, Errors of FC
notation: Slurs