Fix info c <exp> when <exp> doesn't return a constant

[st0012]

Currently, the command info c <exp> crashes the debugger when <exp> is not a constant because it raises an exception. This patch fixes it by changing it to puts.

Before

(rdbg) info c foo    # command
nil
#<RuntimeError: nil (by foo) is not a Module.>
@@@ #<Thread:0x000000010308b138 run>
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:1237:in `backtrace'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:1237:in `block in wait_next_action_'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:1235:in `each'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:1235:in `rescue in wait_next_action_'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:1230:in `wait_next_action_'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:856:in `wait_next_action'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:320:in `suspend'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/thread_client.rb:251:in `on_breakpoint'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/breakpoint.rb:69:in `suspend'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/breakpoint.rb:170:in `block in setup'
 > /Users/hung-wulo/src/github.com/ruby/debug/lib/debug/session.rb:2599:in `debugger'
 > test.rb:9:in `<main>'
....

After

(rdbg) info c foo    # command
eval error: undefined local variable or method `foo' for main:Object
  (rdbg)/test.rb:1:in `<main>'
nil (by foo) is not a Module.

This commit also adds 2 test cases for the info c <exp> usage.

cc @bitwise-aiden

[ko1]

Let's just ignore the error.
Could you update it?

[master]$ exe/rdbg target.rb -e 'i c Objects;; c'
[1, 10] in target.rb
     1|
=>   2| a = 1
     3|
     4| __END__
     5| _th0 = Thread.new{loop{sleep 0.5; p :th0}}
     6| _th1 = Thread.new{loop{sleep 0.5; p :th1}}
     7| loop do
     8|   sleep 0.5
     9|   p :main
    10| end
=>#0    <main> at target.rb:2
(rdbg:commands) i c Objects
eval error: uninitialized constant Objects

Objects
^^^^^^^
  (rdbg)/target.rb:1:in `<main>'
(rdbg:commands) c

diff --git a/lib/debug/thread_client.rb b/lib/debug/thread_client.rb
index cbecdf5..64b3f06 100644
--- a/lib/debug/thread_client.rb
+++ b/lib/debug/thread_client.rb
@@ -607,12 +607,17 @@ module DEBUGGER__

     def get_consts expr = nil, only_self: false, &block
       if expr && !expr.empty?
-        _self = frame_eval(expr)
-        if M_KIND_OF_P.bind_call(_self, Module)
-          iter_consts _self, &block
-          return
+        begin
+          _self = frame_eval(expr, re_raise: true)
+        rescue Exception => e
+          # ignore
         else
-          raise "#{_self.inspect} (by #{expr}) is not a Module."
+          if M_KIND_OF_P.bind_call(_self, Module)
+            iter_consts _self, &block
+            return
+          else
+            puts "#{_self.inspect} (by #{expr}) is not a Module."
+          end
         end
       elsif _self = current_frame&.self
         cs = {}

[st0012]

@bitwise-aiden I think this is and the one in rescue block are leftovers from debugging?