validate_keys=true ignored when the value is array

[dgutov]

Describe the bug

When the unexpected key's value is an array, it is not reported as unexpected. Validation can be marked as successful even.

To Reproduce

$ irb
irb(main):001:0> require 'dry-schema'
=> true
irb(main):002:0> require 'dry/schema/version'
=> true
irb(main):003:0> Dry::Schema::VERSION
=> "1.6.2"
irb(main):004:1* schema = Dry::Schema.define do
irb(main):005:1*   config.validate_keys = true
irb(main):006:1*   
irb(main):007:2*   optional(:address).hash do
irb(main):008:1*   end
irb(main):009:0> end
=> #<Dry::Schema::Processor keys=[{:address=>[]}] rules={:address=>"key?(:address) THEN key[addr...
irb(main):010:0> schema.call(address: {a: 1})
=> #<Dry::Schema::Result{:address=>{}} errors={:address=>{:a=>["is not allowed"]}}>
irb(main):011:0> schema.call(address: {a: [1, 2, 3]})
=> #<Dry::Schema::Result{:address=>{}} errors={}>
irb(main):012:0> schema.call(address: {a: {b: 1}})
=> #<Dry::Schema::Result{:address=>{}} errors={:address=>{:a=>{:b=>["is not allowed"]}}}>
irb(main):013:0> schema.call(address: {a: 'zz'})
=> #<Dry::Schema::Result{:address=>{}} errors={:address=>{:a=>["is not allowed"]}}>

Expected behavior

It should return #<Dry::Schema::Result{:address=>{}} errors={:address=>{:a=>["is not allowed"]}}> in all cases.

BTW, the nested hash behavior also looks wrong. It should not report that the :b key is out of place, it should do that for the parent structure instead. IOW, I expect all of the cases above to return the same value.

My environment

• Affects my production application: YES
• Ruby version: 2.7.2
• OS: Ubuntu 20.04