Having returned to the key of E
major at the beginning of b. 158, Chopin inserted and then deleted in A the naturals to a in this bar (in the right and left hands) and to a1 in b. 159. By contrast, he left the cautionary 
to a2 in the R.H. in b. 161. This version was repeated by all editions. In the main text we add cautionary naturals to a1 in b. 159 and a2 in b. 160-161 and cautionary flats to the L.H. e1/2/3 notes in b. 158-161.
Compare the passage in the sources»
category imprint: Editorial revisions; Corrections & alterations; Source & stylistic information
issues: Cautionary accidentals, Deletions in A, Last key signature sign
notation: Pitch