In `@src/stores/notes.store.ts`:
- Around line 55-63: The code deletes state.notes[id] and then reads
state.notes[id], causing a runtime error; capture the note before mutation. In
the setter used by deleteNote, first assign const note = state.notes[id]; then,
if note exists and has an occurrenceId (check 'occurrenceId' in note &&
note.occurrenceId), delete state.notesByOccurrenceId[note.occurrenceId]; finally
delete state.notes[id]. Refer to state.notes, state.notesByOccurrenceId, and the
delete logic inside the set((state) => { ... }) block to locate and update the
code.

In `@src/stores/occurrences.store.ts`:
- Around line 149-155: The code updates state.occurrences correctly but still
uses the old occurredAt parameter when writing to occurrencesByDate, which
misplaces items if the API returned a new date and can throw if the date bucket
doesn't exist; update the write to use the returned updatedOccurrence.occurredAt
(via toClientOccurrence(updatedOccurrence).occurredAt or directly from
updatedOccurrence), ensure you check/create the occurrencesByDate bucket key
computed with toCalendarDate(updatedOccurredAt).toString() before assigning, and
also consider removing the entry from the old date bucket if the date changed;
update references around the map update, toClientOccurrence, occurrencesByDate
and toCalendarDate calls accordingly.
- Around line 64-74: The code in the state setter computes dateKey from
occurrence.occurredAt.split('T')[0], causing UTC-vs-local bucketing
inconsistency; change it to derive the key from the client-side object the rest
of the store uses by computing dateKey =
clientOccurrence.toCalendarDate().toString() (so addOccurrence, which updates
state.occurrences and state.occurrencesByDate using clientOccurrence and
nextOccurrence.id, will bucket identically to
fetchOccurrences/removeOccurrence/updateOccurrence).

In `@src/stores/notes.store.ts`:
- Around line 92-97: When updating state in set, you must remove any stale
mapping from notesByOccurrenceId when a note's occurrenceId changes or is
removed: read the previous note (state.notes[id]) before overwriting, if it has
an occurrenceId and it differs from updatedNote.occurrenceId delete
state.notesByOccurrenceId[oldNote.occurrenceId]; then assign
state.notes[id]=updatedNote and, if updatedNote has a truthy occurrenceId, set
state.notesByOccurrenceId[updatedNote.occurrenceId]=updatedNote; use the
existing set, notes, notesByOccurrenceId, updatedNote and id identifiers to
locate and implement this logic.
- Around line 55-61: Guard against a missing note before using the "in" operator
on noteToDelete: in the set callback where noteToDelete is assigned from
state.notes[id], first check that noteToDelete is not null/undefined, then check
for the occurrenceId property and its truthiness before deleting from
state.notesByOccurrenceId (i.e., ensure noteToDelete exists, then if
'occurrenceId' in noteToDelete and noteToDelete.occurrenceId is truthy, delete
state.notesByOccurrenceId[noteToDelete.occurrenceId]). This touches the same
block using noteToDelete and state.notesByOccurrenceId in the set(...) function
in notes.store.ts.