evidently none isn't always none

lmfdb/groups/abstract/main.py

@@ -879,7 +879,7 @@ def show_factor(n):
 
 #for irrQ_degree and irrC_degree gives negative value as "-"
 def remove_negatives(n):
-    if n is None:
+    if n is None or  n == "":
         return "?"
     elif int(n) < 1:
         return "-"