IllegalStateException when adding item to the playlist during ad playback

Version

Media3 1.5.1

More version details

No response

Devices that reproduce the issue

Any device

Devices that do not reproduce the issue

No response

Reproducible in the demo app?

Not tested

Reproduction steps

1. Ad MediaItem with a pre-roll ad
2. Observe ad playing
3. Attempt to add another MediaItem using Player.addMediaItem
4. Observe crash

Expected result

No crash

Actual result

Crash with

java.lang.IllegalStateException
at androidx.media3.common.util.Assertions.checkState(Assertions.java:85)
at androidx.media3.exoplayer.ExoPlayerImpl.maskTimelineAndPosition(ExoPlayerImpl.java:2515)
at androidx.media3.exoplayer.ExoPlayerImpl.addMediaSourcesInternal(ExoPlayerImpl.java:2423)
at androidx.media3.exoplayer.ExoPlayerImpl.addMediaSources(ExoPlayerImpl.java:684)
at androidx.media3.exoplayer.ExoPlayerImpl.addMediaItems(ExoPlayerImpl.java:652)
at androidx.media3.common.BasePlayer.addMediaItems(BasePlayer.java:71)
at androidx.media3.common.BasePlayer.addMediaItem(BasePlayer.java:66)

Media

Any stream with a pre-roll ad

Bug Report

• You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.