mrb_protect() to return the exception raised (with the state of true)

mrbgems/mruby-error/src/exception.c

@@ -17,6 +17,7 @@ mrb_protect(mrb_state *mrb, mrb_func_t body, mrb_value data, mrb_bool *state)
     mrb->jmp = prev_jmp;
   } MRB_CATCH(&c_jmp) {
     mrb->jmp = prev_jmp;
+    result = mrb_obj_value(mrb->exc);
     mrb->exc = NULL;
     if (state) { *state = TRUE; }
   } MRB_END_EXC(&c_jmp);

mrbgems/mruby-error/test/exception.rb

 assert 'mrb_protect' do
+  # no failure in protect returns [result, false]
   assert_equal ['test', false] do
     ExceptionTest.mrb_protect { 'test' }
   end
-  assert_equal [nil, true] do
-    ExceptionTest.mrb_protect { raise 'test' }
-  end
+  # failure in protect returns [exception, true]
+  result = ExceptionTest.mrb_protect { raise 'test' }
+  assert_kind_of RuntimeError, result[0]    
+  assert_true result[1]
 end
 
 assert 'mrb_ensure' do