Fix ViewMode related bugs:

- The user will no longer lost their 'ViewMode' option after being updated in the settings.
- The console will not output errors due tot he scroll function when Mosaic mode is on.


Former-commit-id: 97aa6abdc8b864dc7a55dbf03a2e58895ea7613f [formerly ff9e6ff0898f32bd106b644b2e9002b5de45281c] [formerly 556cc12bd5ff1d91776c81f48dd1dceb8bb627b4 [formerly 51104c5ee7]]
Former-commit-id: dd63b2b818a7bd4960a7243866d6b2829f4c03a8 [formerly 45855d70eaa9a2b060d3a89cb70388040ea8e6d9]
Former-commit-id: 6e0ebf10d7fe3e2c234abc9c0ffd447cfbdd7455

http/users.go

@@ -160,6 +160,11 @@ func usersPostHandler(c *fm.Context, w http.ResponseWriter, r *http.Request) (in
 		u.Rules = []*fm.Rule{}
 	}
 
+	// If the view mode is empty, initialize with the default one.
+	if u.ViewMode == "" {
+		u.ViewMode = c.DefaultUser.ViewMode
+	}
+
 	// Initialize commands if not initialized.
 	if u.Commands == nil {
 		u.Commands = []string{}