Fix doSchema lock issue

[takmatsu]

Backgroud

We sometimes faced the panic fatal error: concurrent map read and map write or fatal error: concurrent map iteration and map write.

Investigation

we found the current lock is not enough:

	schemas, ok := s.schemasByPath[path]

this line seems wanted to copy but it's not copy because it's map.

and then, we have the possibility to face a panic like below

concurrent map read and map write :

	schema := schemas[name]

concurrent map iteration and map write :

	for _, check := range schemas {

What is this PR

This PR fixes the above issue by extending lock to the end of this function.