I am having 500 error while indexing

I am having this issue

{
“readyState”: 4,
“responseText”: “There has been a critical error on this website. Learn more about troubleshooting WordPress.”,
“status”: 500,
“statusText”: “error”
}

when i try to index the blog on my website https://phonehungers.com/. This is the first i am going through this problem. Sometime It automatically get fix and index some pages and then after this the same issue started to come.

Is there any solution available plzz guide me ASAP.