trace method can't accept number as first argument

[MasanoriOnishi]

Your environment

• ruby -v: ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x86_64-linux]
• rdbg -v: rdbg 1.7.2

Describe the bug
In the following code, Signal.#trap method is overridden.
https://github.com/ruby/debug/blob/v1.7.2/lib/debug/session.rb#L2520

Although the original trap code can accept Integer, the above can't.

To Reproduce

irb(main):001:0> require 'debug'
=> true
irb(main):002:0> trap(3,1)
/usr/local/bundle/gems/debug-1.7.2/lib/debug/session.rb:2520:in `trap': undefined method `to_sym' for 3:Integer (NoMethodError)

      case sig&.to_sym
              ^^^^^^^^
Did you mean?  to_s
	from (irb):2:in `<main>'
	from /usr/local/bundle/gems/irb-1.6.4/exe/irb:9:in `<top (required)>'
	from /usr/local/bundle/bin/irb:25:in `load'
	from /usr/local/bundle/bin/irb:25:in `<main>'

Expected behavior
trace method should accept number as first argument.