Catch exceptions caused by dynamic SQL

Question

I have a stored procedure which calls another stored procedure using dynamic SQL. A simplified version of the code is provided here.

CREATE DEFINER=`cmdb`@`%` PROCEDURE `testCall`(procName VARCHAR(100))
BEGIN

   DECLARE EXIT HANDLER FOR SQLEXCEPTION 
   BEGIN

       GET DIAGNOSTICS @num = NUMBER;
       GET DIAGNOSTICS CONDITION @num @message = MESSAGE_TEXT, @errNo = RETURNED_SQLSTATE ;
       if @errorMessage is null then
           Set @errorMessage = "No Error Message";
       end if;
       select @errorMessage;
   END;
   select concat("call ", procName, "()") into @proc;
   Prepare stmt FROM @proc;
   Execute stmt;
   deallocate prepare stmt;
END

If intent is to call an arbitrary stored procedure using testCall. When I call testCall with a non-existent SP name as input as following,

call testCall("storedProc4");

I see the following error message:

"No Error Message"

I expect to see something like below:

"PROCEDURE storedproc4 does not exist"

How to catch this exception? I have tried a CONTINUE handler for error 1305 and an EXIT handler as well with the similar results.