Details
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Improvement
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Status: Closed
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Major
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Resolution: Fixed
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None
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None
Description
As documented in https://sling.apache.org/documentation/the-sling-engine/errorhandling.html#resetting-the-response when implementing a customer error handler it is up to the implementation to check whether a response is committed, and to reset the response. If this is not done by the error handler this can result in wrong responses back to the client.
We can make it easier for error handlers, by checking whether the response is already committed and only invoke the error handler if not. And in that case first reset the response. This avoids to rely on the implementor of the error handler doing the right thing but will also not break existing error handlers.
In addition, we should only invoke error handlers if the current response is not an include - in the case of an include the exception should be propagated up the call chain. According to the servlet spec includes are not allowed to set headers or reset the response.