Fix PreserveInlineStylesRule

lib/src/models/rules/insert.dart

@@ -571,7 +571,8 @@ class PreserveInlineStylesRule extends InsertRule {
         final currData = currLine.data as String?;
         if (currData != null && (currData.isEmpty || currData[0] == '\n')) {
           if (prevData.trimRight().isEmpty) {
-            final back = DeltaIterator(documentDelta).skip(index - prevData.length);
+            final back =
+                DeltaIterator(documentDelta).skip(index - prevData.length);
             if (back != null && back.data is String) {
               prev = back;
             }