Simplify concat bulk string logic

Author: Ruben Bridgewater

lib/parser.js

@@ -319,14 +319,14 @@ function concatBulkString (parser) {
     if (chunks === 2) {
       return list[0].toString('utf8', parser.bigOffset, list[0].length - 1)
     }
-  } else {
-    chunks++
+    chunks--
+    offset = list[list.length - 2].length + 1
   }
   var res = decoder.write(list[0].slice(parser.bigOffset))
-  for (var i = 1; i < chunks - 2; i++) {
+  for (var i = 1; i < chunks - 1; i++) {
     res += decoder.write(list[i])
   }
-  res += decoder.end(list[i].slice(0, offset === 1 ? list[i].length - 1 : offset - 2))
+  res += decoder.end(list[i].slice(0, offset - 2))
   return res
 }