Crash when combining QFileSystemModel with QSortFilterProxyModel

I have QfileSysteModel and QSortFilterProxyModel. When I try to call QfileSysteModel.filePath to get the current index of the file Error occurs as core Dump. Here is a piece of code

    le = QLineEdit()
    lv = QListView()

    file_model = QFileSystemModel()
    file_model.setRootPath(QtCore.QDir.rootPath())

    proxy_model = QSortFilterProxyModel(
        recursiveFilteringEnabled=True,
        filterRole=QtWidgets.QFileSystemModel.FileNameRole)
    proxy_model.setSourceModel(file_model)
    lv.setModel(self.proxy_model)

It works well, but when I try to call any methods of the QFileSystemModel Core Dumps. for example

filepath  = file_model.filePath(lv.currentIndex())

How can I use any method of the QfileSystemModel

from PyQt5 import QtCore, QtGui, QtWidgets


class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)

        le = QtWidgets.QLineEdit()
        self.lv = QtWidgets.QListView()

        self.file_model = QtWidgets.QFileSystemModel()
        self.file_model.setRootPath(QtCore.QDir.rootPath())

        self.proxy_model = QtCore.QSortFilterProxyModel(
            recursiveFilteringEnabled=True,
            filterRole=QtWidgets.QFileSystemModel.FileNameRole)
        self.proxy_model.setSourceModel(self.file_model)
        self.lv.setModel(self.proxy_model)
        root_index = self.file_model.index(QtCore.QDir.rootPath())
        proxy_index = self.proxy_model.mapFromSource(root_index)
        self.lv.setRootIndex(proxy_index)
        self.lv.doubleClicked.connect(self.navigate)

        lay = QtWidgets.QVBoxLayout(self)
        lay.addWidget(le)
        lay.addWidget(self.lv)


    def navigate(self):

        # Get the path of file or folder
        filepath  = self.file_model.filePath(self.lv.currentIndex())
        print(filepath)


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

When working with a proxy model, the ModelIndex of the proxy differs from the index in the source model. Use mapToSource() to convert from proxy model to source model.

In your case, it would probably look like this:

# alternative one: do not reference proxy_model directly
filepath = file_model.filePath(lv.model().mapToSource(lv.currentIndex()))
# alternative two:
filepath = file_model.filePath(self.proxy_model.mapToSource(lv.currentIndex()))