yep - looks like the nvidia driver is killing the budgie-window manager

Suggest purge the nvidia driver you have installed for the moment.

this looks relevant:

mar 24 18:14:08 Asus-UbuntuBudgie kernel: NVRM: Xid (PCI:0000:00:0d): 1, Channel 00000002 Method 00000060 Data beef0233
mar 24 18:14:08 Asus-UbuntuBudgie kernel: NVRM: Xid (PCI:0000:00:0d): 1, Channel 00000002 Method 00000060 Data beef0233
mar 24 18:14:08 Asus-UbuntuBudgie kernel: NVRM: Xid (PCI:0000:00:0d): 1, Channel 00000002 Method 00000060 Data beef0233
mar 24 18:14:08 Asus-UbuntuBudgie kernel: NVRM: Xid (PCI:0000:00:0d): 1, Channel 00000002 Method 00000060 Data beef0233
mar 24 18:14:08 Asus-UbuntuBudgie kernel: NVRM: Xid (PCI:0000:00:0d): 1, Channel 00000002 Method 00000060 Data beef0233
mar 24 18:14:08 Asus-UbuntuBudgie budgie-wm[1791]: The program 'budgie-wm' received an X Window System error.
                                                   This probably reflects a bug in the program.
                                                   The error was 'BadMatch (invalid parameter attributes)'.
                                                     (Details: serial 919 error_code 8 request_code 134 (SYNC) minor_code 16)
                                                     (Note to programmers: normally, X errors are reported asynchronously;
                                                      that is, you will receive the error a while after causing it.
                                                      To debug your program, run it with the GDK_SYNCHRONIZE environment
                                                      variable to change this behavior. You can then get a meaningful
                                                      backtrace from your debugger if you break on the gdk_x_error() function.)
mar 24 18:14:08 Asus-UbuntuBudgie kernel: do_trap: 30 callbacks suppressed
mar 24 18:14:08 Asus-UbuntuBudgie kernel: traps: budgie-wm[1791] trap int3 ip:7efbfa36ade1 sp:7ffea31d4d20 error:0
mar 24 18:14:08 Asus-UbuntuBudgie kernel:  in libglib-2.0.so.0.5200.0[7efbfa31b000+111000]
mar 24 18:14:08 Asus-UbuntuBudgie dbus-daemon[1496]: Activating via systemd: service name='org.freedesktop.Tracker1' unit='tracker-store.service'
mar 24 18:14:08 Asus-UbuntuBudgie systemd[1460]: Starting Tracker metadata database store and lookup manager...
mar 24 18:14:08 Asus-UbuntuBudgie gnome-session-binary[1480]: Entering running state
mar 24 18:14:08 Asus-UbuntuBudgie at-spi2-registr[1680]: Failed to register client: GDBus.Error:org.gnome.SessionManager.AlreadyRegistered: Unable to register client
mar 24 18:14:08 Asus-UbuntuBudgie at-spi2-registr[1680]: Unable to register client with session manager
mar 24 18:14:10 Asus-UbuntuBudgie nvidia-settings-autostart.desktop[1877]: ERROR: Error querying target relations
mar 24 18:14:10 Asus-UbuntuBudgie nvidia-settings-autostart.desktop[1877]: ERROR: Error querying target relations
mar 24 18:14:11 Asus-UbuntuBudgie dbus-daemon[1496]: Activating via systemd: service name='org.ayatana.bamf' unit='bamfdaemon.service'
mar 24 18:14:11 Asus-UbuntuBudgie nautilus-autostart.desktop[1895]: sys:1: PyGIWarning: Nautilus was imported without specifying a version first. Use gi.require_version('Nautilus', '3.0') before import to ensure that the right version gets loaded.
mar 24 18:14:11 Asus-UbuntuBudgie systemd[1460]: Starting BAMF Application Matcher Framework...
mar 24 18:14:12 Asus-UbuntuBudgie dbus-daemon[1496]: Successfully activated service 'org.ayatana.bamf'
mar 24 18:14:12 Asus-UbuntuBudgie systemd[1460]: Started BAMF Application Matcher Framework.
mar 24 18:14:15 Asus-UbuntuBudgie dbus-daemon[1496]: Successfully activated service 'org.freedesktop.Tracker1'
mar 24 18:14:15 Asus-UbuntuBudgie systemd[1460]: Started Tracker metadata database store and lookup manager.
mar 24 18:14:15 Asus-UbuntuBudgie tracker-store.desktop[1874]: (uint32 1,)
mar 24 18:14:24 Asus-UbuntuBudgie gnome-session[1480]: gnome-session-binary[1480]: WARNING: Application 'budgie-wm.desktop' killed by signal 5
mar 24 18:14:24 Asus-UbuntuBudgie gnome-session-binary[1480]: WARNING: Application 'budgie-wm.desktop' killed by signal 5

CTRL+ALT+F2
login

sudo apt purge nvidia*

sudo reboot --