Improved stability for chrome debugging

- Display the greeting message regardless of the status of invocation of
  chrome.

  This allows coming back to the debugger on a new tab when the window
  process by `UI_CDP.run_new_chrome` is killed.

- Handle `Errno::ESRCH` in `UI_CDP.cleanup_reader`.

  When the process by `UI_CDP.run_new_chrome` is killed, re-killing it
  breaks your debugging session and in turn the "debugee".

Author: josegomezr

lib/debug/server.rb

@@ -406,14 +406,13 @@ def chrome_setup
       require_relative 'server_cdp'
 
       @uuid = SecureRandom.uuid
-      unless @chrome_pid = UI_CDP.setup_chrome(@local_addr.inspect_sockaddr, @uuid)
-        DEBUGGER__.warn <<~EOS
-          With Chrome browser, type the following URL in the address-bar:
+      @chrome_pid = UI_CDP.setup_chrome(@local_addr.inspect_sockaddr, @uuid)
+      DEBUGGER__.warn <<~EOS
+        With Chrome browser, type the following URL in the address-bar:
 
-             devtools://devtools/bundled/inspector.html?v8only=true&panel=sources&ws=#{@local_addr.inspect_sockaddr}/#{@uuid}
+           devtools://devtools/bundled/inspector.html?v8only=true&panel=sources&ws=#{@local_addr.inspect_sockaddr}/#{@uuid}
 
-          EOS
-      end
+        EOS
     end
 
     def accept

lib/debug/server_cdp.rb

@@ -663,6 +663,7 @@ def deactivate_bp
     def cleanup_reader
       super
       Process.kill :KILL, @chrome_pid if @chrome_pid
+    rescue Errno::ESRCH # continue if @chrome_pid process is not found
     end
 
     ## Called by the SESSION thread