error line: 185 describe the bug and how to correct it. Don't need to correct the code, just explain please.

181. public-EventBook.getEvents(Date date) - {9 182. -> EventBook-events = null;" 183. > 184. --> if (this.date. == date) {9 185. -> events.add(this.name);) 186. 187. 188. return -events:) 189. }