I just tested with the example project, "ble_app_uart" using SDK, "nRF5SDK17009d13099.zip" on nRF52DK (labelled with PCA10040 1.2.4 2018.23) board on Segger embedded studio.
After 5 minutes, "ble_app_uart" project app without any added code is going to down to at the break point in function, "app_error_fault_handler()" on SES as following attached capture shot image.
I think it may have bugs on that example. please let us know how to fix it.
The shot image in case the problem occurs is as following and the image is the captured SES screen with debugging information and call stack.