add detail field for internal error

[WindSoilder]

Hi, I found it would be helpful to show one error's debug information, like this (the following example is using https://github.com/LukeMathWalker/tracing-bunyan-formatter)

[INTERNAL ERROR - EVENT] sent (error="database error occured",http.duration=202.429447ms,http.method=POST,http.status_code=500,http.target=/subscriptions,line=51,target=tide_tracing)
    detail: database error occured

    Caused by:
        0: error returned from database: column "subscription_token" of relation "subscription_tokens" does not exist
        1: column "subscription_token" of relation "subscription_tokens" does not exist
    --
    file: xxxxx

It shows the root cause of one error, which is helpful for debugging.

So I opened this pr to try to attach detail field.

[eopb]

I like this. Thank you!