Java Error

Tried to throw a org/gnome/glib/FatalError but calling FindClass() on that name failed.
DANGER: GLib-GObject-WARNING, cannot register existing type 'GdkDisplayManager'
DANGER: GLib-CRITICAL, g_once_init_leave: assertion 'result != 0' failed
DANGER: GLib-GObject-CRITICAL, g_object_new_with_properties: assertion 'G_TYPE_IS_OBJECT (object_type)' failed
DANGER: GLib-GObject-WARNING, invalid (NULL) pointer instance
DANGER: GLib-GObject-CRITICAL, g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
DANGER: GLib-GObject-WARNING, invalid (NULL) pointer instance
DANGER: GLib-GObject-CRITICAL, g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007f566ed97b2c, pid=9124, tid=0x00007f5700783700
#
DANGER: GLib-GObject-WARNING, cannot register existing type 'GdkDisplay'
DANGER: GLib-CRITICAL, g_once_init_leave: assertion 'result != 0' failed
DANGER: GLib-GObject-CRITICAL, g_type_register_static: assertion 'parent_type > 0' failed
DANGER: GLib-CRITICAL, g_once_init_leave: assertion 'result != 0' failed
DANGER: GLib-GObject-CRITICAL, g_object_new_with_properties: assertion 'G_TYPE_IS_OBJECT (object_type)' failed
# JRE version: Java(TM) SE Runtime Environment (8.0_152-b16) (build 1.8.0_152-b16)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.152-b16 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# C  [libgdk-x11-2.0.so.0+0x4eb2c]  gdk_display_open+0x5c
#
# Core dump written. Default location: /home/spicy/Documents/compsci/Media Player/src/core or core.9124
#
# An error report file with more information is saved as:
# /home/spicy/Documents/compsci/Media Player/src/hs_err_pid9124.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#