don't deleteByDfa when buffer's length is 1, because that would mean that we would be deleting last newline in file

fcore/normal-mode/make-normal-delete.sml

@@ -227,7 +227,10 @@ struct
       finishAfterDeletingBuffer (app, low, buffer, time, initialMsg)
     end
 
-  fun deleteByDfa (app: app_type, count, fMove, time) =
+  fun deleteByDfa (app as {buffer, ...}: app_type, count, fMove, time) =
+    if #textLength buffer = 1 then
+      NormalFinish.clearMode app
+    else
       let
         val {buffer, cursorIdx, ...} = app
 
@@ -235,11 +238,12 @@ struct
         val otherIdx = fMove (buffer, cursorIdx, count)
       in
         if otherIdx > cursorIdx then
+          if otherIdx >= #textLength buffer then
           (* prevent us from deleting last newline
            * to help us preserve unix-style line endings *)
-        if otherIdx > #textLength buffer then
+            let val high = #textLength buffer - 1
-          finishDeleteByDfa
+            in finishDeleteByDfa (app, cursorIdx, high, buffer, time)
-            (app, cursorIdx, #textLength buffer - 1, buffer, time)
+            end
           else
             finishDeleteByDfa (app, cursorIdx, otherIdx, buffer, time)
         else if otherIdx < cursorIdx then