In A (→FE,FC→GE1) there is no 
raising d2 to d
2. Chopin's oversight is evidenced by a comparison with an analogous move in b. 3 and by the sharps added in pencil in three teaching copies, bearing traces of the Prelude having been developed with Chopin – FED (the sign was almost certainly written with Chopin's hand), FES and FESch. In less melodically obvious contexts, it may be difficult to determine whether we are dealing with an overlooked accidental or an intended effect, e.g. in the Sonata in B
Minor, Op. 35, I mov., b. 207, especially since one can encounter chords featuring the interval of a diminished third in Chopin's works, e.g. in the Mazurka in B Minor, Op. 24 No. 4, b. 16, 40 and analog.
In the discussed place, a was added by the revisers of GE2 and EE and most probably also by George Sand in her copy (on the basis of the photocopy of CGS at the disposal of the editors of mUltimate Chopin, it is difficult to clearly interpret the notation; however, it most probably contains two partially overlapping sharps, which suggests that the top one was added later). Both sharps are also in CXI, which seems to confirm that this manuscript comes from another, unknown source.
Compare the passage in the sources »
category imprint: Interpretations within context; Differences between sources
issues: Annotations in teaching copies, EE revisions, Annotations in FED, GE revisions, Errors of A, Annotations in FES, Annotations in FESch, Errors repeated in GE, Errors repeated in FE
notation: Pitch