Fix html messages not rendering at all on markwon exception

If render(): renderAndProcess(markwon.parse(text), _) fails,
the input text *string* is returned instead of a Spannable,
so we shouldn't cast without checking here.

Fixes https://github.com/SchildiChat/SchildiChat-android/issues/201

Change-Id: I1824328e0b733de699a33376833b2fbc86b0e44f

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/factory/MessageItemFactory.kt

@@ -679,8 +679,9 @@ class MessageItemFactory @Inject constructor(
                 ?: matrixFormattedBody
          */
         val compressed = htmlCompressor.compress(matrixFormattedBody)
-        val renderedFormattedBody = htmlRenderer.get().render(compressed, pillsPostProcessor) as Spanned
+        val renderedFormattedBody = htmlRenderer.get().render(compressed, pillsPostProcessor) as? Spanned ?: compressed
-        val pseudoEmojiBody = htmlRenderer.get().render(customToPseudoEmoji(compressed), pillsPostProcessor) as Spanned
+        val pseudoEmojiCompressed = customToPseudoEmoji(compressed)
+        val pseudoEmojiBody = htmlRenderer.get().render(pseudoEmojiCompressed, pillsPostProcessor) as? Spanned ?: pseudoEmojiCompressed
         return buildMessageTextItem(
                 renderedFormattedBody,
                 true,