SL-19635 Better error handling

indra/newview/lltranslate.cpp

@@ -949,6 +949,8 @@ bool LLDeepLTranslationHandler::checkVerificationResponse(
     const LLSD& response,
     int status) const
 {
+    // Might need to parse body to make sure we got
+    // a valid response and not a message
     return status == HTTP_OK;
 }
 
@@ -1000,7 +1002,6 @@ bool LLDeepLTranslationHandler::parseResponse(
     {
         return false;
     }
-    
 
     detected_lang = data["detected_source_language"].asString();
     LLStringUtil::toLower(detected_lang);
@@ -1019,8 +1020,22 @@ bool LLDeepLTranslationHandler::isConfigured() const
 std::string LLDeepLTranslationHandler::parseErrorResponse(
     const std::string& body)
 {
-    // DeepL doesn't seem to have any error handling beyoun http codes
-    return std::string();
+    // Example: "{\"message\":\"One of the request inputs is not valid.\"}"
+
+    Json::Value root;
+    Json::Reader reader;
+
+    if (!reader.parse(body, root))
+    {
+        return std::string();
+    }
+
+    if (!root.isObject() || !root.isMember("message"))
+    {
+        return std::string();
+    }
+
+    return root["message"].asString();
 }
 
 // static

indra/newview/skins/default/xui/en/floater_translation_settings.xml

@@ -319,7 +319,7 @@
      name="deepl_api_domain_label"
      top_pad="80"
      width="85">
-        Domain:
+        Endpoint:
     </text>
 
     <combo_box