Internal navigation should change the CDP loader-id

This is one of the ways that puppeteer knows that navigation happened
and is needed to support `waitForNavigation` which compares the
existing loader-id with the new one, so it has to change.

Also, fix a crash that could happen if CDP disconnects while
connections are being aborted.

src/cdp/domains/page.zig

@@ -163,6 +163,11 @@ pub fn pageNavigate(arena: Allocator, bc: anytype, event: *const Notification.Pa
     std.debug.assert(bc.session.page != null);
 
     var cdp = bc.cdp;
+
+    if (event.opts.reason != .address_bar) {
+        bc.loader_id = bc.cdp.loader_id_gen.next();
+    }
+
     const loader_id = bc.loader_id;
     const target_id = bc.target_id orelse unreachable;
     const session_id = bc.session_id orelse unreachable;