added more specific exceptions

abstracto-application/core/core-interface/src/main/java/dev/sheldan/abstracto/core/exception/UserInServerNotFoundException.java

@@ -0,0 +1,27 @@
+package dev.sheldan.abstracto.core.exception;
+
+import dev.sheldan.abstracto.templating.Templatable;
+
+import java.util.HashMap;
+
+public class UserInServerNotFoundException extends AbstractoRunTimeException implements Templatable {
+
+    private Long userInServerId;
+
+    public UserInServerNotFoundException(Long userInServerId) {
+        super("");
+        this.userInServerId = userInServerId;
+    }
+
+    @Override
+    public String getTemplateName() {
+        return "core_user_in_server_not_found_exception";
+    }
+
+    @Override
+    public Object getTemplateModel() {
+        HashMap<String, Long> param = new HashMap<>();
+        param.put("userInServerId", this.userInServerId);
+        return param;
+    }
+}