Don't crash if CSV web importer does not receive a file

todo/views/import_csv.py

@@ -1,10 +1,12 @@
+from django.contrib import messages
 from django.contrib.auth.decorators import login_required, user_passes_test
 from django.http import HttpResponse
-from django.shortcuts import render
-from todo.operations.csv_importer import CSVImporter
+from django.shortcuts import redirect, render, reverse
 
+from todo.operations.csv_importer import CSVImporter
 from todo.utils import staff_check
 
+
 @login_required
 @user_passes_test(staff_check)
 def import_csv(request) -> HttpResponse:
@@ -14,7 +16,12 @@ def import_csv(request) -> HttpResponse:
     ctx = {}
 
     if request.method == "POST":
-        filepath = request.FILES.get('csvfile')
+        filepath = request.FILES.get("csvfile")
+
+        if not filepath:
+            messages.error(request, "You must supply a CSV file to import.")
+            return redirect(reverse("todo:import_csv"))
+
         importer = CSVImporter()
         results = importer.upsert(filepath)
         ctx["results"] = results