BUG: triggered 'if (axnum >= dev->valuator->numAxes)'

I have a Surface Pro 3, and I'm using evdev to use it. While looking to tackle another issue (my trackpad suddenly stopped working), I noticed this in the xorg log:

[ 3479.176] (II) XINPUT: Adding extended input device "Microsoft Surface Type Cover" (type: KEYBOARD, id 8)
[ 3479.176] (**) Option "xkb_rules" "evdev"
[ 3479.176] (**) Option "xkb_model" "pc105"
[ 3479.176] (**) Option "xkb_layout" "us"
[ 3479.176] (WW) evdev: Microsoft Surface Type Cover: touchpads, tablets and touchscreens ignore relative axes.
[ 3479.176] (EE) BUG: triggered 'if (axnum >= dev->valuator->numAxes)'
[ 3479.176] (EE) BUG: ../../Xi/exevents.c:2086 in InitValuatorAxisStruct()
[ 3479.176] (EE)
[ 3479.176] (EE) Backtrace:
[ 3479.176] (EE) 0: /usr/bin/X (xorg_backtrace+0x56) [0x7f8c9d098f76]
[ 3479.176] (EE) 1: /usr/bin/X (InitValuatorAxisStruct+0x67) [0x7f8c9d0280c7]
[ 3479.176] (EE) 2: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f8c9476d000+0x51c2) [0x7f8c947721c2]
[ 3479.176] (EE) 3: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f8c9476d000+0x5406) [0x7f8c94772406]
[ 3479.176] (EE) 4: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f8c9476d000+0x7088) [0x7f8c94774088]
[ 3479.177] (EE) 5: /usr/bin/X (ActivateDevice+0x4a) [0x7f8c9cf2e50a]
[ 3479.177] (EE) 6: /usr/bin/X (0x7f8c9cee2000+0xa4d91) [0x7f8c9cf86d91]
[ 3479.177] (EE) 7: /usr/bin/X (0x7f8c9cee2000+0xbb8e9) [0x7f8c9cf9d8e9]
[ 3479.177] (EE) 8: /usr/bin/X (0x7f8c9cee2000+0xbbc28) [0x7f8c9cf9dc28]
[ 3479.177] (EE) 9: /usr/bin/X (WakeupHandler+0x6b) [0x7f8c9cf3e24b]
[ 3479.177] (EE) 10: /usr/bin/X (WaitForSomething+0x1c7) [0x7f8c9d096327]
[ 3479.177] (EE) 11: /usr/bin/X (0x7f8c9cee2000+0x57311) [0x7f8c9cf39311]
[ 3479.177] (EE) 12: /usr/bin/X (0x7f8c9cee2000+0x5b706) [0x7f8c9cf3d706]
[ 3479.177] (EE) 13: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf5) [0x7f8c9ac37ec5]
[ 3479.177] (EE) 14: /usr/bin/X (0x7f8c9cee2000+0x45a8e) [0x7f8c9cf27a8e]
[ 3479.177] (EE)
[ 3479.177] (EE) BUG: triggered 'if (axnum >= dev->valuator->numAxes)'
[ 3479.177] (EE) BUG: ../../Xi/exevents.c:2119 in SetScrollValuator()
[ 3479.177] (EE)
[ 3479.177] (EE) Backtrace:
[ 3479.177] (EE) 0: /usr/bin/X (xorg_backtrace+0x56) [0x7f8c9d098f76]
[ 3479.177] (EE) 1: /usr/bin/X (SetScrollValuator+0x76) [0x7f8c9d027ea6]
[ 3479.177] (EE) 2: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f8c9476d000+0x51ee) [0x7f8c947721ee]
[ 3479.177] (EE) 3: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f8c9476d000+0x5406) [0x7f8c94772406]
[ 3479.177] (EE) 4: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f8c9476d000+0x7088) [0x7f8c94774088]
[ 3479.177] (EE) 5: /usr/bin/X (ActivateDevice+0x4a) [0x7f8c9cf2e50a]
[ 3479.177] (EE) 6: /usr/bin/X (0x7f8c9cee2000+0xa4d91) [0x7f8c9cf86d91]
[ 3479.177] (EE) 7: /usr/bin/X (0x7f8c9cee2000+0xbb8e9) [0x7f8c9cf9d8e9]
[ 3479.177] (EE) 8: /usr/bin/X (0x7f8c9cee2000+0xbbc28) [0x7f8c9cf9dc28]
[ 3479.177] (EE) 9: /usr/bin/X (WakeupHandler+0x6b) [0x7f8c9cf3e24b]
[ 3479.177] (EE) 10: /usr/bin/X (WaitForSomething+0x1c7) [0x7f8c9d096327]
[ 3479.177] (EE) 11: /usr/bin/X (0x7f8c9cee2000+0x57311) [0x7f8c9cf39311]
[ 3479.177] (EE) 12: /usr/bin/X (0x7f8c9cee2000+0x5b706) [0x7f8c9cf3d706]
[ 3479.177] (EE) 13: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf5) [0x7f8c9ac37ec5]
[ 3479.177] (EE) 14: /usr/bin/X (0x7f8c9cee2000+0x45a8e) [0x7f8c9cf27a8e]
[ 3479.177] (EE)
[ 3479.178] (II) evdev: Microsoft Surface Type Cover: initialized for absolute axes.
[ 3479.178] (**) Microsoft Surface Type Cover: (accel) keeping acceleration scheme 1
[ 3479.178] (**) Microsoft Surface Type Cover: (accel) acceleration profile 0
[ 3479.178] (**) Microsoft Surface Type Cover: (accel) acceleration factor: 2.000
[ 3479.178] (**) Microsoft Surface Type Cover: (accel) acceleration threshold: 4

I have the similar lines in the beginning of the log also (with timestamp around 5), and I don't understand why all this is repeated here also.

I suffer also from:
https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/954426

Trying to switch to console mode then come back doesn't trigger these lines.

This report is only about this BUG behing logged into Xorg file. But it might be of interest of noting that I'm chasing an sudden issue with my typecover : the trackpad stopped working. For now, this is probably unrelated.