fix for a crash with the following steps.

- open file sel
- save user defaults
- new file
- ctrl+u (crash)

wasn't type checking the space file, passed info space to ED_fileselect_exit().

source/blender/editors/screen/screen_edit.c

@@ -1133,7 +1133,10 @@ void ED_area_exit(bContext *C, ScrArea *sa)
 	ARegion *ar;
 
 	if (sa->spacetype == SPACE_FILE) {
-		ED_fileselect_exit(C, (SpaceFile*)(sa) ? sa->spacedata.first : CTX_wm_space_data(C));
+		SpaceLink *sl= sa->spacedata.first;
+		if(sl && sl->spacetype == SPACE_FILE) {
+			ED_fileselect_exit(C, (SpaceFile *)sl);
+		}
 	}
 
 	CTX_wm_area_set(C, sa);

source/blender/editors/space_file/file_ops.c

@@ -854,7 +854,7 @@ int file_next_exec(bContext *C, wmOperator *UNUSED(unused))
 		folderlist_pushdir(sfile->folders_prev, sfile->params->dir);
 		folderlist_popdir(sfile->folders_next, sfile->params->dir);
 
-		// update folder_prev so we can check for it in folderlist_clear_next()
+		// update folders_prev so we can check for it in folderlist_clear_next()
 		folderlist_pushdir(sfile->folders_prev, sfile->params->dir);
 
 		file_change_dir(C, 1);

source/blender/editors/space_file/filelist.c

@@ -469,13 +469,12 @@ int folderlist_clear_next(struct SpaceFile *sfile)
 /* not listbase itself */
 void folderlist_free(ListBase* folderlist)
 {
-	FolderList *folder;
 	if (folderlist){
+		FolderList *folder;
 		for(folder= folderlist->first; folder; folder= folder->next)
 			MEM_freeN(folder->foldername);
 		BLI_freelistN(folderlist);
 	}
-	folderlist= NULL;
 }
 
 ListBase *folderlist_duplicate(ListBase* folderlist)

source/blender/editors/space_file/filesel.c

@@ -655,9 +655,10 @@ void ED_fileselect_clear(struct bContext *C, struct SpaceFile *sfile)
 void ED_fileselect_exit(struct bContext *C, struct SpaceFile *sfile)
 {
 	if(!sfile) return;
-	if(sfile->op)
+	if(sfile->op) {
 		WM_event_fileselect_event(C, sfile->op, EVT_FILESELECT_EXTERNAL_CANCEL);
-	sfile->op = NULL;
+		sfile->op = NULL;
+	}
 
 	folderlist_free(sfile->folders_prev);
 	folderlist_free(sfile->folders_next);