Pull request review thread start line must precede the end line

[parkerbxyz]

Sometimes this action fails with the following error:

Pull request review thread start line must precede the end line

Here's the debug output from a workflow run that failed with this error:

diff --git a/README.md b/README.md
index 35de41f..2f8d74e 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1 @@
-# test-repo!
-test
-
+# test-repo
@@ -4,0 +3 @@ test
+test

Starting line: 1
Number of lines: 3
Changes: [{"type":"DeletedLine","lineBefore":1,"content":"# test-repo!"},{"type":"DeletedLine","lineBefore":2,"content":"test"},{"type":"DeletedLine","lineBefore":3,"content":""},{"type":"AddedLine","lineAfter":1,"content":"# test-repo"}]
Starting line: 4
Number of lines: 0
Changes: [{"type":"AddedLine","lineAfter":3,"content":"test"}]

To fix this, we need to handle cases where the number of lines in a chunk is 0. In such cases, we should treat the start_line and [end] line as the same line.