Comment 2 for bug 1502347

The error seems to occur when SPObject::requestModified (in src/sp-object.cpp:1166) is called from sp_style_filter_ref_modified (in src/sp-style.cpp:1284) with an object that was already released (tested in debug mode, with some additional code, and the object's ID is the same in SPObject::release and in SPObject::requestModified):

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/home/nicolas/dev/bzr/inkscape/trunk/src/sp-object.cpp(612) release:id=0x5d4ed10, typename=(null)

** (inkscape:23048): WARNING **: entering 'sp_style_filter_ref_modified'
/home/nicolas/dev/bzr/inkscape/trunk/src/sp-object.cpp(1168) requestModified:id=0x5d4ed10, typename=(null)

** (inkscape:23048): CRITICAL **: void SPObject::requestModified(unsigned int): assertion 'this->document != NULL' failed
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