Plugin_SN_Basis/main.py

from qgis.PyQt.QtCore import QCoreApplication
from qgis.PyQt.QtGui import QIcon
from sn_basis.ui.navigation import Navigation
from sn_basis.ui.dockmanager import DockManager

class BasisPlugin:
    def __init__(self, iface):
        self.iface = iface
        self.ui = None
        self.quitting = False
        QCoreApplication.instance().aboutToQuit.connect(self._on_quit)

    def _on_quit(self):
        self.quitting = True

    def initGui(self):
        self.ui = Navigation(self.iface)

    def unload(self):
        if not self.quitting and self.ui:
            self.ui.remove_all()