SSIS-Wrong value in Configuration file overridden by Parameter Default ?

Hi ,

I am new to SSIS so please explain below scenario.I am running via VS2015.

I have SSIS 2012 created which has some config values and same name with Parameters.

Example:

User::Name -Which expects string 

Parameter have same "Name" with Default Value "John"

If I give correct expected type say for example "Marry " in the Config SSIS fetch Marry from config file  and process the package.

If I give wrong type int or special characters  say eg: 123434 like .Its not throwing error but fetch default value "John" value from parameter and process without error.

Please let me know the behavior.