Changed shm:get key nil check order

Changed so the key != nil check is done before flags are are set, this
makes it so function with (ok, err) return struct have old
functionality.

Author: Miniwoffer

lib/resty/core/shdict.lua

@@ -296,17 +296,17 @@ end
 local function shdict_get(zone, key, flags)
     zone = check_zone(zone)
 
+    if key == nil then
+        return nil, "nil key"
+    end
+
     if flags ~= nil then
         user_flags_neq[0] = 1
         user_flags[0] = flags
     else
         user_flags_neq[0] = 0
     end
 
-    if key == nil then
-        return nil, "nil key"
-    end
-
     if type(key) ~= "string" then
         key = tostring(key)
     end
@@ -382,17 +382,17 @@ end
 local function shdict_get_stale(zone, key, flags)
     zone = check_zone(zone)
 
+    if key == nil then
+        return nil, "nil key"
+    end
+
     if flags ~= nil then
         user_flags_neq[0] = 1
         user_flags[0] = flags
     else
         user_flags_neq[0] = 0
     end
 
-    if key == nil then
-        return nil, "nil key"
-    end
-
     if type(key) ~= "string" then
         key = tostring(key)
     end