Change Linq query to pull an item out that isn't used to instead check if the index is out of range of the array

Author: dplarina

src/LZString.cs

@@ -302,8 +302,7 @@ public static string decompress(string compressed)
                         numBits++;
                     }
 
-
-                    if (dictionary.ElementAtOrDefault((int)c) != null) // if (dictionary[c] ) <------- original Javascript Equivalant
+                    if (dictionary.Count - 1 >= c) // if (dictionary[c] ) <------- original Javascript Equivalant
                     {
                         entry = dictionary[c];
                     }