fix(android): correct insertion boundary in FormattingStore and add serializer bounds check (#279)

Author: hryhoriiK97

android/src/main/java/com/swmansion/enriched/markdown/input/formatting/FormattingStore.kt

@@ -140,7 +140,7 @@ class FormattingStore {
         }
       } else {
         when {
-          range.start > editLocation -> {
+          range.start >= editLocation -> {
             range.start += insertedLength
             range.end += insertedLength
           }

android/src/main/java/com/swmansion/enriched/markdown/input/formatting/MarkdownSerializer.kt

@@ -12,8 +12,10 @@ object MarkdownSerializer {
 
     val events = ArrayList<BoundaryEvent>(ranges.size * 2)
     for (range in ranges) {
-      var start = range.start
-      var end = range.end
+      var start = range.start.coerceIn(0, text.length)
+      var end = range.end.coerceIn(0, text.length)
+
+      if (start >= end) continue
 
       // Trim leading/trailing whitespace so delimiters hug non-whitespace content
       while (start < end && text[start].isWhitespace()) start++