[24.0] Reset content-length for unhandled exceptions

[mvdbeek]

This prevents ProtocolError caused by the error middleware not being able to reset the content length. Only affects routes that explicitly set the content-length and don't have a default response handler.

This is effectively the case when using web.expose. To test this, make sure you get Galaxy's error middleware output in the browser and your console if you apply the diff below and navigate to http://127.0.0.1:8080/dataset/imp.

diff --git a/lib/galaxy/webapps/galaxy/controllers/dataset.py b/lib/galaxy/webapps/galaxy/controllers/dataset.py
index c95d9df788..92b04684d3 100644
--- a/lib/galaxy/webapps/galaxy/controllers/dataset.py
+++ b/lib/galaxy/webapps/galaxy/controllers/dataset.py
@@ -456,6 +456,8 @@ class DatasetInterface(BaseUIController, UsesAnnotations, UsesItemRatings, UsesE
     def imp(self, trans, dataset_id=None, **kwd):
         """Import another user's dataset via a shared URL; dataset is added to user's current history."""
         # Set referer message.
+        trans.response.headers["content-length"] = 0
+        trans = None
         referer = trans.request.referer
         if referer and not referer.startswith(f"{trans.request.application_url}{url_for('/login')}"):
             referer_message = f"<a href='{escape(referer)}'>return to the previous page</a>"

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