[Register objects table] Use the last known school term if there is no current school term

(cherry picked from commit 4468aa1b)

aleksis/apps/alsijil/forms.py

@@ -296,8 +296,14 @@ class FilterRegisterObjectForm(forms.Form):
     def get_initial(cls, has_documentation: Optional[bool] = None):
         date_end = timezone.now().date()
         date_start = date_end - timedelta(days=30)
+        school_term = SchoolTerm.current
+
+        # If there is no current school year, use last known school year.
+        if not school_term:
+            school_term = SchoolTerm.objects.all().last()
+
         return {
-            "school_term": SchoolTerm.current,
+            "school_term": school_term,
             "date_start": date_start,
             "date_end": date_end,
             "has_documentation": has_documentation,

aleksis/apps/alsijil/util/alsijil_helpers.py

@@ -336,6 +336,11 @@ def generate_list_of_all_register_objects(filter_dict: Dict[str, Any]) -> List[D
     # Always force a value for school term, start and end date so that queries won't get too big
     initial_filter_data = FilterRegisterObjectForm.get_initial()
     filter_dict["school_term"] = filter_dict.get("school_term", initial_filter_data["school_term"])
+
+    # If there is not school year at all, there are definitely no data.
+    if not filter_dict["school_term"]:
+        return []
+
     filter_dict["date_start"] = filter_dict.get("date_start", initial_filter_data["date_start"])
     filter_dict["date_end"] = filter_dict.get("date_end", initial_filter_data["date_end"])
     filter_dict["filter_date"] = bool(filter_dict.get("date_start")) and bool(