Returning NULL from gui_download_window_create causes crash

Hi all I've found another stop/abort type crash :( Returning NULL from gui_download_window_create causes NetSurf to crash, rather than just aborting the pending download. Logs attached. Stack trace line numbers: 9.Files:Projects/netsurf_svn/netsurf> a2l netsurf-cairo 753a0 desktop/download.c:274 9.Files:Projects/netsurf_svn/netsurf> a2l netsurf-cairo 751b0 desktop/download.c:206 9.Files:Projects/netsurf_svn/netsurf> a2l netsurf-cairo 569bc content/llcache.c:1476 9.Files:Projects/netsurf_svn/netsurf> a2l netsurf-cairo 5474c content/llcache.c:314 9.Files:Projects/netsurf_svn/netsurf> a2l netsurf-cairo 531d0 content/hlcache.c:183