[route]

A worker target without a session, such as a service worker Ferrum detached from or a worker whose session was detached, broke Context#workers and Target#worker. Target#worker built a Worker on session(nil) and failed with CDP's "Message may have string 'sessionId' property", and Context#workers listed dead workers or raised the same error.

Fix

• Context#workers skips worker and shared worker targets without a session. Since fix(context): reuse the session of an attached target in attach_target #668 the session id is cleared on detach, so this covers detached workers.
• Target#worker raises NoSuchTargetError when there's no session, pointing to Context#attach_target. Only in flatten mode, the non-flatten one connects by target id.

Test

spec/worker_spec.rb:

• A dedicated worker detached through the page session drops out of browser.workers. Without the fix it stays listed.
• target.worker on a service worker Ferrum detached from raises NoSuchTargetError. Without the fix it raises the CDP error.