Add a workaround for a possible null offset ID.

app/src/test/java/org/schabi/newpipe/ktx/OffsetDateTimeToCalendarTest.kt

@@ -0,0 +1,31 @@
+package org.schabi.newpipe.ktx
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import java.time.LocalDate
+import java.time.OffsetDateTime
+import java.time.ZoneId
+import java.time.ZoneOffset
+import java.util.Calendar
+import java.util.TimeZone
+
+class OffsetDateTimeToCalendarTest {
+    @Test
+    fun testRelativeTimeWithCurrentOffsetDateTime() {
+        val calendar = LocalDate.of(2020, 1, 1).atStartOfDay().atOffset(ZoneOffset.UTC)
+                .toCalendar()
+
+        assertEquals(2020, calendar[Calendar.YEAR])
+        assertEquals(0, calendar[Calendar.MONTH])
+        assertEquals(1, calendar[Calendar.DAY_OF_MONTH])
+        assertEquals(0, calendar[Calendar.HOUR])
+        assertEquals(0, calendar[Calendar.MINUTE])
+        assertEquals(0, calendar[Calendar.SECOND])
+        assertEquals(TimeZone.getTimeZone("UTC"), calendar.timeZone)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testRelativeTimeWithFarOffOffsetDateTime() {
+        OffsetDateTime.MAX.minusYears(1).toCalendar()
+    }
+}