Add error message for empty source language

share/translations/screentranslator_ru.ts

@@ -706,6 +706,14 @@ in %1</source>
         <translation>Ошибка инициализации OCR: %1</translation>
     </message>
 </context>
+<context>
+    <name>Recognizer</name>
+    <message>
+        <location filename="../../src/ocr/recognizer.cpp" line="36"/>
+        <source>No source language set. Check settings</source>
+        <translation>Не задан исходный язык. Проверьте настройки</translation>
+    </message>
+</context>
 <context>
     <name>ResultEditor</name>
     <message>

src/ocr/recognizer.cpp

@@ -32,6 +32,12 @@ void Recognizer::recognize(const TaskPtr &task)
   SOFT_ASSERT(task, return );
   SOFT_ASSERT(task->isValid(), return );
 
+  if (task->sourceLanguage.isEmpty()) {
+    task->error = tr("No source language set. Check settings");
+    manager_.recognized(task);
+    return;
+  }
+
   queue_.push_back(task);
   if (queue_.size() == 1)
     processQueue();