Analysis: Resolve non exhaustive when statements test when warning

Warning Message: "Non exhaustive 'when' statements on enum will be
prohibited in 1.7, add 'Xyz', 'Xyz' branch(es) or 'else' branch instead"

Also, as part of this commit, one other minor warning got resolved too.

Author: ParaskP7

WordPress/src/test/java/org/wordpress/android/ui/mediapicker/MediaPickerViewModelTest.kt

@@ -286,7 +286,7 @@ class MediaPickerViewModelTest : BaseUnitTest() {
         viewModel.refreshData(false)
 
         assertThat(navigateEvents).isEmpty()
-        clickItem(0)
+        clickItem()
         assertThat(navigateEvents).isNotEmpty
         verify(mediaPickerTracker).trackPreview(
                 firstItem.type == VIDEO,
@@ -724,11 +724,12 @@ class MediaPickerViewModelTest : BaseUnitTest() {
             is PhotoItem -> item.toggleAction.toggle()
             is VideoItem -> item.toggleAction.toggle()
             is FileItem -> item.toggleAction.toggle()
+            is NextPageLoader -> Unit // Do nothing
         }
     }
 
-    private fun clickItem(position: Int) {
-        when (val item = itemOnPosition(position)) {
+    private fun clickItem() {
+        when (val item = itemOnPosition(0)) {
             is PhotoItem -> item.clickAction.click()
             is VideoItem -> item.clickAction.click()
             is FileItem -> item.clickAction.click()