fix : crash si aucunes questions

Blazor/Blazor/Pages/Questions/Questions.razor.cs

@@ -101,10 +101,12 @@ public partial class Questions
                 selectedQuestions.Add(questions[i]);
             }
             questions = selectedQuestions;
-
+            if (!response.IsNullOrEmpty())
+            {
                 totalQuestion = response[0].total_questions;
             }
         }
+    }
 
     private async Task Export()
     {
@@ -126,9 +128,10 @@ public partial class Questions
         {
             await e.File.OpenReadStream().CopyToAsync(ms);
             var bytes = ms.ToArray();
-            string s = Encoding.UTF8.GetString(bytes);
+            string s = Encoding.Unicode.GetString(bytes);
 
             s = s.Replace("\"", string.Empty);
+            s = s.Replace("\0", string.Empty);
             var rows = s.Split('\n');
             rows = rows.Skip(1).ToArray();