In Player:HasProperRepLevel(): Make sure a given rep isn't nil.

diff --git a/Player.lua b/Player.lua
index 10b188e..075372a 100644
--- a/Player.lua
+++ b/Player.lua
@@ -112,7 +112,7 @@ function Player:HasProperRepLevel(rep_data)
 			end
 			local rep_name = private.reputation_list[rep_id].name

-			if player_rep[rep_name] < rep_level then
+			if player_rep[rep_name] and player_rep[rep_name] < rep_level then
 				has_faction = false
 			else
 				has_faction = true