The fact that the slur is not continued in a new line in FE is most probably an oversight by the engraver, and it was interpreted as such in the remaining editions. A longer slur is also present in AI, which allows us to recognise this version as the only one intended by Chopin.
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, Errors in FE, GE revisions
notation: Slurs