Fix MAL error when list entries have partial dates (#3573)

This has the side effect of forcing the date to something concrete.

For Year-only: 1st of January that year
Ex: 2025 -> 2025-01-01

For Year+Month: 1st of said month
Ex: 2024-11 -> 2024-11-01

MAL allows setting Day+Month and Day+Year, but both of those are sent
as `null` in the API, which means Mihon will not show a date at all.
This has the side effect of Mihon sending up the date as `null` the
next time info is sent to MAL, which will clear the date fields
completely.

Co-authored-by: AntsyLich <59261191+AntsyLich@users.noreply.github.com>

CHANGELOG.md

@@ -25,6 +25,7 @@ The format is a modified version of [Keep a Changelog](https://keepachangelog.co
 - Fixed extension installation with shizuku installer ([@NGB-Was-Taken](https://github.com/NGB-Was-Taken)) ([#3676](https://github.com/mihonapp/mihon/pull/3676))
 - Fixed `X-Requested-With` spoofing leaking to unrelated callers ([@AntsyLich](https://github.com/AntsyLich)) ([#3678](https://github.com/mihonapp/mihon/pull/3678))
 - Fixed reader loading indefinitely in some scenarios ([@AntsyLich](https://github.com/AntsyLich)) ([#3686](https://github.com/mihonapp/mihon/pull/3686))
+- Fix MyAnimeList error for list entries with partial start/finish reading dates by setting those dates to either Jan 1st or 1st of the month ([@MajorTanya](https://github.com/MajorTanya)) ([#3573](https://github.com/mihonapp/mihon/pull/3573))
 
 ## [v0.20.2] - 2026-08-01
 ### Added

app/src/main/java/eu/kanade/tachiyomi/data/track/myanimelist/MyAnimeListApi.kt

@@ -245,7 +245,13 @@ class MyAnimeListApi(
     }
 
     private fun parseDate(isoDate: String): Long {
-        return SimpleDateFormat("yyyy-MM-dd", Locale.US).parse(isoDate)?.time ?: 0L
+        val pattern = when (isoDate.length) {
+            10 -> "yyyy-MM-dd"
+            7 -> "yyyy-MM"
+            4 -> "yyyy"
+            else -> throw IllegalArgumentException("Unsupported date format: \"$isoDate\"")
+        }
+        return SimpleDateFormat(pattern, Locale.US).parse(isoDate)?.time ?: 0L
     }
 
     private fun convertToIsoDate(epochTime: Long): String? {