Fix sysadmin delete

src/main/java/dev/kruhlmann/imgfloat/controller/SystemAdministratorApiController.java

@@ -57,7 +57,11 @@ public class SystemAdministratorApiController {
             throw new ResponseStatusException(BAD_REQUEST, "Username is required");
         }
         String username = request.twitchUsername().trim();
-        systemAdministratorService.addSysadmin(username);
+        try {
+            systemAdministratorService.addSysadmin(username);
+        } catch (IllegalStateException e) {
+            throw new ResponseStatusException(BAD_REQUEST, e.getMessage(), e);
+        }
         LOG.info("System administrator added: {} (requested by {})", username, sessionUsername);
         return ResponseEntity.ok().body(systemAdministratorService.listSysadmins());
     }

src/main/java/dev/kruhlmann/imgfloat/service/SystemAdministratorService.java

@@ -71,7 +71,7 @@ public class SystemAdministratorService {
         String initialSysadmin = getInitialSysadmin();
 
         if (initialSysadmin != null && initialSysadmin.equals(normalized)) {
-            return;
+            throw new IllegalStateException("Cannot add the initial system administrator");
         }
 
         if (repo.existsByTwitchUsername(normalized)) {
@@ -81,6 +81,7 @@ public class SystemAdministratorService {
         repo.save(new SystemAdministrator(normalized));
     }
 
+    @Transactional
     public void removeSysadmin(String twitchUsername) {
         String normalized = normalize(twitchUsername);
         String initialSysadmin = getInitialSysadmin();
@@ -118,11 +119,21 @@ public class SystemAdministratorService {
     }
 
     public List<String> listSysadmins() {
-        return repo
+        String initialSysadmin = getInitialSysadmin();
+        List<String> persistedAdmins = repo
             .findAllByOrderByTwitchUsernameAsc()
             .stream()
             .map(SystemAdministrator::getTwitchUsername)
             .collect(Collectors.toList());
+        if (initialSysadmin == null) {
+            return persistedAdmins;
+        }
+        return java.util.stream.Stream
+            .concat(persistedAdmins.stream(), java.util.stream.Stream.of(initialSysadmin))
+            .map(this::normalize)
+            .distinct()
+            .sorted()
+            .collect(Collectors.toList());
     }
 
     private String normalize(String username) {

src/main/resources/static/js/settings.js

@@ -187,14 +187,16 @@ function renderSystemAdministrators(admins) {
         const button = document.createElement("button");
         button.classList.add("button", "secondary");
         button.type = "button";
-        button.textContent = "Remove";
-        button.addEventListener("click", () => removeSystemAdministrator(admin));
         button.setAttribute("data-sysadmin-remove", "true");
         button.setAttribute("data-sysadmin-username", admin);
 
         if (isInitialSysadmin) {
             button.disabled = true;
-            button.title = "The initial system administrator cannot be removed.";
+            button.textContent = "System default";
+            button.title = "The system default administrator cannot be removed.";
+        } else {
+            button.textContent = "Remove";
+            button.addEventListener("click", () => removeSystemAdministrator(admin));
         }
 
         listItem.appendChild(text);
@@ -226,6 +228,10 @@ function addSystemAdministrator() {
         showToast("Enter a Twitch username", "warning");
         return;
     }
+    if (initialSysadmin && username.toLowerCase() === initialSysadmin) {
+        showToast("That user is already the system default administrator.", "warning");
+        return;
+    }
     fetch("/api/system-administrators", {
         method: "POST",
         headers: { "Content-Type": "application/json" },