500 - Oops, There is server error

/home/test2/client/clients/blogs/views/blog-details.html:183 181|

182|
>> 183| <%= blogData.comments[i].user_id.admin.name.first %> 184| <%= blogData.comments[i].user_id.admin.name.last %> 185| <%= blogData.comments[i].inserted.on %> 186|
Cannot read property 'name' of null