Describe the bug

Calling sinon.stub() from Node.js running with --disable-proto=throw causes Error to be thrown.

To Reproduce

1. Run node --disable-proto=throw -e "require('sinon').stub()" in a project with sinon 21.1 installed.

2. Observe the output similar to the following:

   /path/to/node_modules/sinon/lib/sinon/util/core/walk.js:29
           if (seen[k] !== true) {
                   ^
   
   Error: Accessing Object.prototype.__proto__ has been disallowed with --disable-proto=throw
       at /path/to/node_modules/sinon/lib/sinon/util/core/walk.js:29:17
       at Array.forEach (<anonymous>)
       at walkInternal (/path/to/node_modules/sinon/lib/sinon/util/core/walk.js:28:5)
       at walkInternal (/path/to/node_modules/sinon/lib/sinon/util/core/walk.js:41:9)
       at walkInternal (/path/to/node_modules/sinon/lib/sinon/util/core/walk.js:41:9)
       at walk (/path/to/node_modules/sinon/lib/sinon/util/core/walk.js:57:12)
       at collectOwnMethods (/path/to/node_modules/sinon/lib/sinon/collect-own-methods.js:39:5)
       at addReturnedMethodsToCollection (/path/to/node_modules/sinon/lib/sinon/sandbox.js:196:21)
       at Sandbox.stub (/path/to/node_modules/sinon/lib/sinon/sandbox.js:229:9)
       at [eval]:1:18 {
     code: 'ERR_PROTO_ACCESS'
   }
   

Expected behavior
The process would produce no output and exit with code 0, as it does with sinon 21.0.3 and earlier.

Context (please complete the following information):

• Sinon version : 21.1.1
• Runtime: Node 25

Additional context

I realize running with --disable-proto=throw may not be a supported scenario, and I understand if you choose not to fix this issue. However, I have found it useful for my own projects to flag use of __proto__ and thought it may be worth considering, given that it worked previously.

Thanks for considering,
Kevin