Bluetooth : fix for crashing alertDialogbox

- changes for crashing of alertDialogbox while displaying message
- in showError function, this fix code shoud be added in case of showing error pop up

Bug: 5068089
Change-Id: I40e8a699461832b7bd47080b40f467572632d412
Signed-off-by: jhtop.kim <jhtop.kim@samsung.com>