Fix crash on empty status messages (#1402)

app/src/main/java/com/keylesspalace/tusky/util/SmartLengthInputFilter.kt

@@ -38,7 +38,8 @@ private const val LENGTH_DEFAULT = 500
  * @return        Whether the message should be trimmed or not.
  */
 fun shouldTrimStatus(message: Spanned): Boolean {
-	return LENGTH_DEFAULT / message.length > 0.75
+    // Check for emptiness so that we don't divide by zero
+	return message.isNotEmpty() && LENGTH_DEFAULT.toFloat() / message.length > 0.75
 }
 
 /**