Fix for viewing invalid person.

www/app.js

@@ -356,6 +356,13 @@ function displayFullSchedule() {
 }
 
 function displayIndividualSchedule(person) {
+  if (person.kind === 'staff' && !schedule.all_staff.includes(person.name)
+      || person.kind === 'student' && !schedule.all_students.includes(person.name)) {
+    updateHash({person: undefined});
+    displaySchedule();
+    return;
+  }
+
   if (hash.day) {
     const grid = schedule.gridFor(person, hash.day);
     const title = document.createElement('h1');
@@ -446,6 +453,9 @@ async function refreshDisplay() {
 
 function displaySchedule() {
   utils.clearChildren(schedulesDiv);
+  if (hash.day && !schedule.all_days.includes(hash.day)) {
+    updateHash({day: undefined});
+  }
   if (!hash.person) {
     displayFullSchedule();
   } else if (hash.person.kind) {