Fixes to out of bounds for loops

src/notebook.cc

@@ -379,7 +379,7 @@ void Notebook::toggle_split() {
     show_all();
   }
   else {
-    for(size_t c=size();c!=static_cast<size_t>(-1);--c) {
+    for(size_t c=size()-1;c!=static_cast<size_t>(-1);--c) {
       auto notebook_index=get_notebook_page(c).first;
       if(notebook_index==1 && !close(c))
         return;

src/window.cc

@@ -872,7 +872,7 @@ bool Window::on_key_press_event(GdkEventKey *event) {
 bool Window::on_delete_event(GdkEventAny *event) {
   Notebook::get().save_session();
   
-  for(size_t c=Notebook::get().size();c!=static_cast<size_t>(-1);--c) {
+  for(size_t c=Notebook::get().size()-1;c!=static_cast<size_t>(-1);--c) {
     if(!Notebook::get().close(c))
       return true;
   }