I have configured the canvas on the ubuntu server by following the "production start" instruction. 

Production Start · instructure/canvas-lms Wiki · GitHub 

But when I am accessing the public JWKS URL https://canvas.pitchvantage.com/api/lti/security/jwks to access LTI 1.3 tool it is throwing this error while(1);{"errors":[{"message":"An error occurred.","error_code":"internal_server_error"}],"error_report_id":122}
When I am checking the error log it is saying "#122 undefined method `to_key' for nil:NilClass".

Please help me to fix the issue or guide me on how I can use the public JWKS URL for my LTI 1.3 Tool.

Note: I am using this LTI1.3 tool example on my localhost GitHub - IMSGlobal/lti-1-3-php-example-tool