in 
When interpreted literally, the chord on the 3rd beat of the bar in A (→FC) consists of the following notes: F
1-F-b
-d1-f1, which, in turn, results in a G major chord (F major), which could be a part of this harmonic sequence. However, Chopin would generally avoid such an unnatural orthography; therefore, he most probably overlooked here the naturals lowering all f notes to f. They were added both in FE (→EE) and GE, and the composer did not question the printed naturals in any of the three teaching copies containing annotations coming from him.
Compare the passage in the sources »
category imprint: Interpretations within context; Differences between sources
issues: GE revisions, Omission of current key accidentals, Errors of A, FE revisions
notation: Pitch