Fix use of shutil.copytree when overriding existing template files …

…in `tmp_dir` (#2133)

* Fix use of shutil.copytree when overriding existing template files in tmp_dir

* [automated] Update CHANGELOG.md

---------

Co-authored-by: MultiQC Bot <multiqc-bot@seqera.io>

CHANGELOG.md

@@ -30,6 +30,7 @@ Highlights:
 - Just run CI on the oldest + newest supported Python versions ([#2074](https://github.com/ewels/MultiQC/pull/2074))
 - <img src="./multiqc/templates/default/assets/img/favicon-16x16.png" alt="///" width="10px"/> New logo
 - Set name and anchor for the custom content "module" [#2131](https://github.com/ewels/MultiQC/pull/2131)
+- Fix use of `shutil.copytree` when overriding existing template files in `tmp_dir` ([#2133](https://github.com/ewels/MultiQC/pull/2133))
 
 ### New Modules
 

multiqc/multiqc.py

@@ -1063,9 +1063,10 @@ def __rich_measure__(self, console: rich.console.Console, options: rich.console.
         # Load in parent template files first if a child theme
         try:
             parent_template = config.avail_templates[template_mod.template_parent].load()
-            shutil.copytree(parent_template.template_dir, tmp_dir)
         except AttributeError:
             pass  # Not a child theme
+        else:
+            shutil.copytree(parent_template.template_dir, tmp_dir, dirs_exist_ok=True)
 
         # Copy the template files to the tmp directory (`dirs_exist_ok` makes sure
         # parent template files are overwritten)