Don't purge users if unable to load permission data

src/main/java/fr/xephi/authme/permission/handlers/LuckPermsHandler.java

@@ -189,22 +189,21 @@ public class LuckPermsHandler implements PermissionHandler {
     }
 
     @Override
-    public void loadUserData(UUID uuid) {
+    public void loadUserData(UUID uuid) throws PermissionLoadUserException {
         try {
             luckPermsApi.getUserManager().loadUser(uuid).get(5, TimeUnit.SECONDS);
         } catch (InterruptedException | ExecutionException | TimeoutException e) {
-            e.printStackTrace();
+            throw new PermissionLoadUserException("Unable to load the permission data of the user " + uuid, e);
         }
     }
 
     @Override
-    public void loadUserData(String name) {
+    public void loadUserData(String name) throws PermissionLoadUserException {
         try {
             UUID uuid = luckPermsApi.getStorage().getUUID(name).get(5, TimeUnit.SECONDS);
             loadUserData(uuid);
         } catch (InterruptedException | ExecutionException | TimeoutException e) {
-            e.printStackTrace();
+            throw new PermissionLoadUserException("Unable to load the permission data of the user " + name, e);
         }
     }
-
 }

src/main/java/fr/xephi/authme/permission/handlers/PermissionHandler.java

@@ -107,10 +107,9 @@ public interface PermissionHandler {
      */
     PermissionsSystemType getPermissionSystem();
 
-    default void loadUserData(UUID uuid) {
+    default void loadUserData(UUID uuid) throws PermissionLoadUserException {
     }
 
-    default void loadUserData(String name) {
+    default void loadUserData(String name) throws PermissionLoadUserException {
     }
-
 }

src/main/java/fr/xephi/authme/permission/handlers/PermissionLoadUserException.java

@@ -0,0 +1,13 @@
+package fr.xephi.authme.permission.handlers;
+
+import java.util.UUID;
+
+/**
+ * Exception thrown when a {@link PermissionHandler#loadUserData(UUID uuid)} request fails.
+ */
+public class PermissionLoadUserException extends Exception {
+
+    public PermissionLoadUserException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}