Update webstats_common.lua

plugins/webstats/lua/webstats_common.lua

@@ -200,8 +200,9 @@ end
 
 function _M.get_http_origin(self)
     local data = ""
-    local headers = ngx.req.get_headers()
+    local method = ngx.req.get_method()
     if not headers then return data end
+    local headers = ngx.req.get_headers()
     if method ~='GET' then 
         -- API disabled in the context of log_by_lua*
         -- ngx.req.read_body()