Python pyqt5 program crashes when trying to get data from checkbox combo box

New to python so sorry for the terrible code but I'm trying to change something in my code when the user selects a checkbox from the combo box but the program crashes when I try. I can load the table fine but when I try to get the data in my LoadCombo(self): method the program crashes. Thanks for any advice

from PyQt5 import QtGui, QtCore, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QFileDialog, QTableView, QTableWidget, qApp
from PyQt5.QtCore import Qt, QModelIndex, QAbstractTableModel, QSortFilterProxyModel
import sys, os


class Ui_MainWindow(object):
def setupUi(self, MainWindow):
    MainWindow.setObjectName("MainWindow")
    MainWindow.resize(800, 600)
    self.centralwidget = QtWidgets.QWidget(MainWindow)
    self.centralwidget.setObjectName("centralwidget")
    self.tabWidget = QtWidgets.QTabWidget(self.centralwidget)
    self.tabWidget.setGeometry(QtCore.QRect(90, 50, 691, 491))
    self.tabWidget.setObjectName("tabWidget")
    self.tab = QtWidgets.QWidget()
    self.tab.setObjectName("tab")
    self.verticalLayoutWidget = QtWidgets.QWidget(self.tab)
    self.verticalLayoutWidget.setGeometry(QtCore.QRect(70, 50, 491, 331))
    self.verticalLayoutWidget.setObjectName("verticalLayoutWidget")
    self.verticalLayout = QtWidgets.QVBoxLayout(self.verticalLayoutWidget)
    self.verticalLayout.setContentsMargins(0, 0, 0, 0)
    self.verticalLayout.setObjectName("verticalLayout")
    self.horizontalLayout = QtWidgets.QHBoxLayout()
    self.horizontalLayout.setObjectName("horizontalLayout")
    spacerItem = QtWidgets.QSpacerItem(40, 20, QtWidgets.QSizePolicy.Expanding, QtWidgets.QSizePolicy.Minimum)
    self.horizontalLayout.addItem(spacerItem)
    self.testcombo = CheckableComboBox(self.verticalLayoutWidget)
    self.testcombo.setObjectName("testcombo")
    self.horizontalLayout.addWidget(self.testcombo)
    spacerItem1 = QtWidgets.QSpacerItem(40, 20, QtWidgets.QSizePolicy.Expanding, QtWidgets.QSizePolicy.Minimum)
    self.testcombo1 = CheckableComboBox(self.verticalLayoutWidget)
    self.testcombo1.setObjectName("testcombo1")
    for i in range(3):
        self.testcombo1.addItem("Combobox Item " + str(i))
    self.horizontalLayout.addWidget(self.testcombo)
    self.horizontalLayout.addItem(spacerItem1)
    self.verticalLayout.addLayout(self.horizontalLayout)
    self.pushButton = QtWidgets.QPushButton(self.verticalLayoutWidget)
    self.pushButton.setObjectName("pushButton")
    self.pushButton.clicked.connect(self.LoadTable)
    #self.testcombo.itemChecked.connect(self.LoadTable)
    self.verticalLayout.addWidget(self.pushButton)
    self.table = QtWidgets.QTableView()
    self.LoadTable()
    self.proxyModel = QSortFilterProxyModel()
    self.proxyModel.setSourceModel(self.model)
    self.table.setSortingEnabled(True)
    self.table.setModel(self.proxyModel)
    self.verticalLayout.addWidget(self.table)
    self.LoadCombo()
    self.tabWidget.addTab(self.tab, "")
    self.tab_2 = QtWidgets.QWidget()
    self.tab_2.setObjectName("tab_2")
    self.tabWidget.addTab(self.tab_2, "")
    MainWindow.setCentralWidget(self.centralwidget)
    self.menubar = QtWidgets.QMenuBar(MainWindow)
    self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
    self.menubar.setObjectName("menubar")
    MainWindow.setMenuBar(self.menubar)
    self.statusbar = QtWidgets.QStatusBar(MainWindow)
    self.statusbar.setObjectName("statusbar")
    MainWindow.setStatusBar(self.statusbar)
    self.LoadComboBoxes()
    self.retranslateUi(MainWindow)
    QtCore.QMetaObject.connectSlotsByName(MainWindow)

def retranslateUi(self, MainWindow):
    _translate = QtCore.QCoreApplication.translate
    MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
    self.pushButton.setText(_translate("MainWindow", "Load Table"))
    self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab), _translate("MainWindow", "Tab 1"))
    self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab_2), _translate("MainWindow", "Tab 2"))

def LoadTable(self):
    #print(self.testcombo.currentData())
    #self.headerData(['Column 1test', 'Column 2test', 'Column 3', 'test'], Qt.Horizontal, Qt.DisplayRole)

    data = [self.testcombo.currentData()]
    #print(data)
    headers = []
    for x in self.testcombo.currentData():
        headers.append(x+'TESTING!')

    print(headers)
    #headers = self.testcombo.currentData()
    self.model = TableModel(data, headers)
    self.proxyModel = QSortFilterProxyModel()
    self.proxyModel.setSourceModel(self.model)
    #self.table.setSortingEnabled(True)
    self.table.setModel(self.proxyModel)
    #self.setCentralWidget(self.table)

def LoadCombo(self):
    #As soon as I uncomment the below the program crashes when I select a checkbox
    #print(self.testcombo.currentData())
    print('test')


def LoadComboBoxes(self):
    for i in range(6):
        self.testcombo.addItem("Combobox Item " + str(i))



class CheckableComboBox(QtWidgets.QComboBox, Ui_MainWindow):
def __init__(self, parent=None):
    super(CheckableComboBox, self).__init__(parent)
    self.view().pressed.connect(self.handleItemPressed)

    # once there is a checkState set, it is rendered
# here we assume default Unchecked
def addItem(self, item):
    super(CheckableComboBox, self).addItem(item)
    item = self.model().item(self.count()-1,0)
    #item.setFlags(QtCore.Qt.ItemIsUserCheckable | QtCore.Qt.ItemIsEnabled)
    item.setFlags(QtCore.Qt.ItemIsEnabled)
    item.setCheckState(QtCore.Qt.Unchecked)

def handleItemPressed(self, index):
    self.LoadCombo()
    item = self.model().itemFromIndex(index)

    # checking if item is checked
    if item.checkState() == Qt.Checked:

        # making it unchecked
        item.setCheckState(Qt.Unchecked)

        # if not checked
    else:
        # making the item checked
        item.setCheckState(Qt.Checked)

def itemChecked(self, index):
    item = self.model().item(i,0)
    return item.checkState() == QtCore.Qt.Checked

def currentData(self):
    # Return the list of selected items data
    res = []
    for i in range(self.model().rowCount()):
        if self.model().item(i).checkState() == Qt.Checked:
            res.append(self.model().item(i).text())
    return res



class TableModel(QtCore.QAbstractTableModel):

def __init__(self, data, headers):
    super(TableModel, self).__init__()
    self._data = data
    self.header_labels = headers

def data(self, index, role):
    if role == Qt.DisplayRole:
        # See below for the nested-list data structure.
        # .row() indexes into the outer list,
        # .column() indexes into the sub-list
        return self._data[index.row()][index.column()]

def headerData(self, section, orientation, role=Qt.DisplayRole):
    if role == Qt.DisplayRole and orientation == Qt.Horizontal:
        return self.header_labels[section]
    return QAbstractTableModel.headerData(self, section, orientation, role)

def rowCount(self, index):
    # The length of the outer list.
    return len(self._data)

def columnCount(self, index):
    # The following takes the first sub-list, and returns
    # the length (only works if all rows are an equal length)
    return len(self._data[0])


if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())