skip "\n" from `$stdin` before showing prompt

[ko1]

Any input into $stdin before showing prompt will be appear on the next prompt, and entering new empty line will dispatch previous command.

This patch consumes empty lines ("\n"+) from $stdin just before showing the prompt.

[launchable-app[bot]]

:x: Tests Failed

:heavy_multiplication_x:no tests failed :heavy_check_mark:675 tests passed(5 flakes)

[ko1]

Not sure but we need to revisit testing framework.