Fix UnhandledPromiseRejection warning when logging on an ignored path

[qswitcher]

Description

A few days ago I ran into a bug where logging via request.log would cause unhandled promise rejection warnings on routes with disabled logging. I traced it down to this line. Basically on an ignored route, current is equal to the nullLogger which doesn't have a levels property.

Steps to reproduce

• Add a request.log([level]) statement within a route handler such that level is a valid log level configured within hapi-pino such as 'info', 'warn', 'error', etc.
• Disable that route by adding it to ignorePaths
• Make a request to that route

I've added a unit test which reproduces this bug.

[coveralls]

Coverage increased (+0.05%) to 98.861% when pulling b8549d0 on qswitcher:ignore-path-fix into 79ad1b4 on pinojs:master.

[coveralls]

Coverage increased (+0.05%) to 98.861% when pulling b8549d0 on qswitcher:ignore-path-fix into 79ad1b4 on pinojs:master.

[mcollina]

LGTM, good work!