Using GNOME 3.28 beta, Xorg Server 1.20 rc1 and latest xf86-input-libinput release. When I enable two-finger scroll through gnome-control-center, and try to use it in, say, evolution the xorg server crashes with the following backtrace:

Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: Xorg: ../libinput-1.10.2/src/evdev-mt-touchpad-tap.c:1028: int tp_tap_handle_state(struct tp_dispatch *, uint64_t): Assertion `tp->tap.nfingers_down >= 1' failed.
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE)
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) Backtrace:
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 0: /usr/libexec/Xorg (OsInit+0x35a) [0x5b9dba]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 1: /usr/lib/libpthread.so.0 (funlockfile+0x50) [0x7fefbf94aeaf]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 2: /usr/lib/libc.so.6 (gsignal+0x10b) [0x7fefbf3afd6b]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 3: /usr/lib/libc.so.6 (abort+0x151) [0x7fefbf3b1101]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 4: /usr/lib/libc.so.6 (uselocale+0x33a) [0x7fefbf3a8b0a]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 5: /usr/lib/libc.so.6 (__assert_fail+0x42) [0x7fefbf3a8992]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 6: /usr/lib/libinput.so.10 (libinput_device_config_rotation_get_default_angle+0xe4fa) [0x7fefa85ec31a]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 7: /usr/lib/libinput.so.10 (libinput_device_config_rotation_get_default_angle+0xd4f1) [0x7fefa85e8841]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 8: /usr/lib/libinput.so.10 (libinput_device_config_rotation_get_default_angle+0xab37) [0x7fefa85e5257]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 9: /usr/lib/libinput.so.10 (libinput_device_config_rotation_get_default_angle+0x48d9) [0x7fefa85d8de9]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 10: /usr/lib/libinput.so.10 (libinput_device_config_rotation_get_default_angle+0x317b) [0x7fefa85d5f5b]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 11: /usr/lib/libinput.so.10 (libinput_dispatch+0x5f) [0x7fefa85ccc8f]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 12: /usr/lib/xorg/modules/input/libinput_drv.so (_init+0x3708) [0x7fefb0224ff8]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 13: /usr/libexec/Xorg (xthread_sigmask+0xb9) [0x5b8169]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 14: /usr/libexec/Xorg (OsCleanup+0x5f3) [0x5ba673]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 15: /usr/libexec/Xorg (input_force_unlock+0x74e) [0x5b836e]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 16: /usr/lib/libpthread.so.0 (__pthread_get_minstack+0x135a) [0x7fefbf94179a]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) 17: /usr/lib/libc.so.6 (clone+0x3f) [0x7fefbf471958]
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE)
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE)
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: Fatal server error:
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) Caught signal 6 (Aborted). Server aborting
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE)
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: Please consult the The X.Org Foundation support
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]:          at http://wiki.x.org
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]:  for help.
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE) Please also check the log file at "/home/armin/.local/share/xorg/Xorg.0.log" for additional information.
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (EE)
Mar 11 12:39:27 krejzi /usr/libexec/gdm-x-session[19398]: (II) AIGLX: Suspending AIGLX clients for VT switch