EFname.c: potential dereference of a null pointer

Theoretical NULL pointer deref, assumes no iteration occurs.
Seems like false positive from incorrect caller use, from
passing suffix==NULL.

SonarCloud
Access to field 'hn_parent' results in a dereference of a null pointer (loaded from variable 'prev')
https://sonarcloud.io/project/issues?open=AZJB167jNGfDNup0RjGu&id=dlmiles_magic

extflat/EFname.c

@@ -189,7 +189,8 @@ EFHNConcat(prefix, suffix)
 	else
 	    firstNew = new;
     }
-    prev->hn_parent = prefix;
+    if (prev)
+	prev->hn_parent = prefix;
 
     return firstNew;
 }