Should I type the diagnosis?

No. The tool asks whether you have the record. A diagnosis, an image and an identity number are not asked.

Does a mark mean an error was found?

No. A complication is not malpractice by itself. The list does not decide fault.

https://www.112.gov.tr/112 is for immediate physical danger. It is not a legal filing desk and not a diagnosis.
https://www.saglik.gov.tr/The ministry home page is not the patient-file desk of a hospital.
https://enabiz.gov.tr/e-Nabız is the person's own record portal. It is not a malpractice complaint and not every hospital file.
https://www.mevzuat.gov.tr/mevzuat?MevzuatNo=4847&MevzuatTur=7&MevzuatTertip=5The Patient Rights Regulation is the text. It does not choose a court.
https://www.mevzuat.gov.tr/mevzuat?MevzuatNo=6698&MevzuatTur=1&MevzuatTertip=5The personal-data statute is not the malpractice desk.
https://www.kvkk.gov.tr/The data-protection authority is not the place that issues a patient file.
https://www.atk.gov.tr/The forensic medicine institution is not the first door for a copy of the hospital file.
https://www.resmigazete.gov.tr/The Official Gazette publishes texts. It does not receive a patient-file request.