Fix crash on AttachmentViewer (#2365)

Not sure how to reproduce it, but if the value is -1, it will crash for sure

CHANGES.md

@@ -8,6 +8,7 @@ Improvements 🙌:
  - Open an existing DM instead of creating a new one (#2319)
 
 Bugfix 🐛:
+ - Fix crash on AttachmentViewer (#2365)
  - Fix issue when updating the avatar of a room (new avatar vanishing)
  - Discard change dialog displayed by mistake when avatar has been updated
 

vector/src/main/java/im/vector/app/features/media/VectorAttachmentViewerActivity.kt

@@ -119,7 +119,7 @@ class VectorAttachmentViewerActivity : AttachmentViewerActivity(), BaseAttachmen
         val inMemoryData = intent.getParcelableArrayListExtra<AttachmentData>(EXTRA_IN_MEMORY_DATA)
         if (inMemoryData != null) {
             val sourceProvider = dataSourceFactory.createProvider(inMemoryData, room)
-            initialIndex = inMemoryData.indexOfFirst { it.eventId == args.eventId }
+            initialIndex = inMemoryData.indexOfFirst { it.eventId == args.eventId }.coerceAtLeast(0)
             sourceProvider.interactionListener = this
             setSourceProvider(sourceProvider)
             this.currentSourceProvider = sourceProvider
@@ -132,7 +132,7 @@ class VectorAttachmentViewerActivity : AttachmentViewerActivity(), BaseAttachmen
             }
         } else {
             val events = room?.getAttachmentMessages().orEmpty()
-            initialIndex = events.indexOfFirst { it.eventId == args.eventId }
+            initialIndex = events.indexOfFirst { it.eventId == args.eventId }.coerceAtLeast(0)
             val sourceProvider = dataSourceFactory.createProvider(events)
             sourceProvider.interactionListener = this
             setSourceProvider(sourceProvider)