gh-36888: Fix failure of doc preview changes when an html is removed

    
Fixes #36887.

Tested with #36892 and #36885.

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- #36871

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URL: #36888
Reported by: Kwankyu Lee
Reviewer(s):

.ci/create-changes-html.sh

@@ -62,10 +62,12 @@ for block in diff_blocks:
     match = re.search(r'^diff --git a/(.*) b/\1', block, flags=re.MULTILINE)
     if match:
         doc = match.group(1)
-        path = 'html/' + doc
         file_path = os.path.join('$DOC_REPOSITORY', doc)
-        with open(file_path, 'r') as file:
-            content = file.readlines()
+        try:
+            with open(file_path, 'r') as file:
+                content = file.readlines()
+        except FileNotFoundError:
+            content = []
         count = 0
         for line in block.splitlines():
             if line.startswith('@@ -'):
@@ -77,8 +79,10 @@ for block in diff_blocks:
                             count += 1
                             content[i] = f'<span id="hunk{count}" style="visibility: hidden;"></span>' + content[i]
                             break
-        with open(file_path, 'w') as file:
-            file.writelines(content)
+        if content:
+            with open(file_path, 'w') as file:
+                file.writelines(content)
+        path = 'html/' + doc
         hunks = '&nbsp;'.join(f'<a href="{path}#hunk{i+1}" class="hunk" target="_blank">#{i + 1}</a>' for i in range(count))
         out_blocks.append(f'<p class="diff"><a href="{path}">{doc}</a>&nbsp;' + hunks + '&emsp;</p>'
                             + '\n<pre><code class="language-diff">'