Debugging PyQt5 module

[Rich Shepard]

I'm writing a business tracking application for my own use. I've used the
database with the psql shell for several years and decided it's the
application for me to learn PyQt5.

The application has three lookup tables and I'm using them to learn the
model/view pattern and SQL access.

The actitytypes table used in the attached code has these values:
  Phone
  Email
  Fax
  Meeting
  Conference
  Referral
  Called me
  Other

When I run the module (python3-3.7.2) a blank window displays; no content at
all. I need to learn why.

How do I debug (as distinct from a unittest) a PyQt5 application?

TIA,

Rich

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import sys
from PyQt5 import QtWidgets as qtw
from PyQt5 import QtGui as qtg
from PyQt5 import QtCore as qtc
from PyQt5 import QtSql as qts

class MainWindow(qtw.QMainWindow):

    def __init__(self):
        super().__init__()

        # Set up database connection
        self.db = qts.QSqlDatabase.addDatabase('QPSQL')
        self.db.setDatabaseName('bustrac')
        if not self.db.open():
            error = self.db.lastError().text()
            qtw.QMessageBox.critical(
                None, 'DB Connection Error',
                'Could not open database file: '
                f'{error}')
            sys.exit(1)

            tables = set('activities','activitytypes','industrytypes',
                         'locations','organizations','organizations_org_nbr_seq',
                         'people','people_person_nbr_seq','projects','statustypes')
        
            # Check that all database tables exist
            required_tables = {'activities','activitytypes','industrytypes',
                               'locations','organizations','organizations_org_nbr_seq',
                               'people','people_person_nbr_seq','projects','statustypes'}
            tables = self.db.tables()
            missing_tables = required_tables - set(tables)
            if missing_tables:
                qtw.QMessageBox.critica(
                    None, 'DB Integrity Error'
                    'Missing tables, please repair DB: '
                    f'{missing_tables}')
                sys.exit(1)

        # Model/View here.
        self.table = qtw.QTableView()
        
        self.model = qts.QSqlTableModel(db=self.db) # for single table

        self.table.setModel(self.model)

        self.model.setTable('activitytypes')
        self.model.select()

        self.setFixedSize(800, 600)
        self.setCentralWidget(self.table)

        
if __name__ == '__main__':
    app = qtw.QApplication(sys.argv)
    window = MainWindow()
    window.show()
    #sys.exit(app.exec())
    app.exec_()