kate prints A LOT of completely useless information to stdout or stderr, which then end up in ~/.xsession-errors and cause that file to grow to a ridiculous size.

Every time you type it prints stuff like:

kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::installedMovingRanges: [ (161, 0)  ->  (161, 41) ]
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::deleteMovingRange: [ (161, 14)  ->  (161, 24) ]
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::removeRangeFromEverything: [ (161, 14)  ->  (161, 24) ]  ( [ (161, 14)  ->  (161, 24) ]  )
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::queueLineSpellCheck: KateDocument(0x8e4e6c8) [ (161, 4)  ->  (161, 41) ]
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::addToSpellCheckQueue: KateDocument(0x8e4e6c8) [ (161, 4)  ->  (161, 41) ]  ""
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::addToSpellCheckQueue: added [ (161, 4)  ->  (161, 41) ]  "" to the queue, which has a length of 5
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::performSpellCheck: for the range  [ (161, 4)  ->  (161, 41) ]
kate(6876)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::installedMovingRanges: [ (161, 4)  ->  (161, 41) ]
kate(6876)/Kate (On-The-Fly Spellcheck) 

Merely changing the currently selected file also spams a good deal:

kate(6876)/kate-filetree KateFileTreeModel::documentActivated: END!
kate(6876)/kate-filetree KateFileTreePluginView::viewChanged: END!
kate(6876)/kate-filetree KateFileTreeModel::documentNameChanged: END!
kate(6876)/kate-filetree KateFileTreeModel::documentModifiedChanged: BEGIN!
kate(6876)/kate-filetree KateFileTreeModel::documentModifiedChanged: saved!
kate(6876)/kate-filetree KateFileTreeModel::setupIcon: BEGIN!
kate(6876)/kate-filetree KateFileTreeModel::setupIcon: END!
kate(6876)/kate-filetree KateFileTreeModel::documentModifiedChanged: END!

All of this might be useful for debugging kate, but other than that, it doesn't help the user to spot errors by looking into the xsession-errors file.

I'm not quite sure what defines what is supposed to go into xsession-errors, but here's e.g. what GNOME thinks: ".xsession-errors is ideally empty all the time.  UI programs aren't supposed to write to stdout/stderr, so when they do it's normally for exceptional reasons."
(https://mail.gnome.org/archives/gdm-list/2007-November/msg00017.html)

Reproducible: Always

Actual Results:  
Spam.

Expected Results:  
Should print actual errors or warnings only.