Fix for unsupported courses

app/src/main/java/gr/thmmy/mthmmy/activities/upload/UploadActivity.java

@@ -940,6 +940,7 @@ public class UploadActivity extends BaseActivity {
             String retrievedCourse = maybeCourse.replaceAll("-", "").replace("(ΝΠΣ)", "").trim();
             String retrievedSemester = maybeSemester.replaceAll("-", "").trim().substring(0, 1);
 
+            if(!retrievedCourse.isEmpty()){
                 UploadsCourse foundUploadsCourse = UploadsCourse.findCourse(retrievedCourse, uploadsCourses);
 
                 if(foundUploadsCourse != null){
@@ -949,6 +950,7 @@ public class UploadActivity extends BaseActivity {
                     titleDescriptionBuilderButton.setEnabled(true);
                     return;
                 }
+            }
 
             titleDescriptionBuilderButton.setEnabled(false);
         }