TypeError after right mouse click

[mariansam]

The program crashes after a right mouse click with the traceback

Traceback (most recent call last):
  File "/home/marian/.local/lib/python3.9/site-packages/grafatko/__init__.py", line 291, in mouseReleaseEvent
    pressed_vertices = self.graph.vertices_at_position(self.mouse.get_position())
  File "/home/marian/.local/lib/python3.9/site-packages/grafatko/graph.py", line 937, in vertices_at_position
    if vertex._get_weight_box(self.is_directed()).contains(*position):
  File "/home/marian/.local/lib/python3.9/site-packages/grafatko/graph.py", line 654, in _get_weight_box
    metrics = QFontMetrics(self.font)
TypeError: arguments did not match any overloaded call:
  QFontMetrics(QFont): argument 1 has unexpected type 'NoneType'
  QFontMetrics(QFont, QPaintDevice): argument 1 has unexpected type 'NoneType'
  QFontMetrics(QFontMetrics): argument 1 has unexpected type 'NoneType'

This happens with graphs of any size, I was able to make something like this before the crash:

But it also crashed after right-clicking with something like this:

The program was installed using pip3 install grafatko, defaulting to the user installation directory. Some info about the versions:

Version output

marian@thiccpad  ~$ pip show grafatko
Name: grafatko
Version: 0.2.5
Summary: An app for creating and visualizing graphs and graph-related algorithms.
Home-page: https://github.com/xiaoxiae/Grafatko
Author: Tomáš Sláma
Author-email: tomas@slama.dev
License: UNKNOWN
Location: /home/marian/.local/lib/python3.9/site-packages
Requires: pyqt5, qtmodern
Required-by:
marian@thiccpad  ~$ pip show pyqt5
Name: PyQt5
Version: 5.15.2
Summary: Python bindings for the Qt cross platform application toolkit
Home-page: https://www.riverbankcomputing.com/software/pyqt/
Author: Riverbank Computing Limited
Author-email: info@riverbankcomputing.com
License: GPL v3
Location: /home/marian/.local/lib/python3.9/site-packages
Requires: PyQt5-sip
Required-by: grafatko
marian@thiccpad  ~$ pip show PyQt5-sip
Name: PyQt5-sip
Version: 12.8.1
Summary: The sip module support for PyQt5
Home-page: https://www.riverbankcomputing.com/software/sip/
Author: Riverbank Computing Limited
Author-email: info@riverbankcomputing.com
License: SIP
Location: /home/marian/.local/lib/python3.9/site-packages
Requires:
Required-by: PyQt5
marian@thiccpad  ~$ pip show qtmodern
Name: qtmodern
Version: 0.2.0
Summary: Qt Widgets Modern User Interface
Home-page: https://www.github.com/gmarull/qtmodern
Author: Gerard Marull-Paretas
Author-email: gerardmarull@gmail.com
License: MIT
Location: /home/marian/.local/lib/python3.9/site-packages
Requires: qtpy
Required-by: grafatko
marian@thiccpad  ~$ pip show qtpy
Name: QtPy
Version: 1.9.0
Summary: Provides an abstraction layer on top of the various Qt bindings (PyQt5, PyQt4 and PySide) and additional custom QWidgets.
Home-page: https://github.com/spyder-ide/qtpy
Author: Colin Duquesnoy, The Spyder Development Team
Author-email: goanpeca@gmail.com
License: MIT
Location: /home/marian/.local/lib/python3.9/site-packages
Requires:
Required-by: qtmodern
marian@thiccpad  ~$ pip3 --version
pip 20.2.1 from /usr/lib/python3.9/site-packages/pip (python 3.9)
marian@thiccpad  ~$ python3 --version
Python 3.9.0
marian@thiccpad  ~$

[xiaoxiae]

It seems that I'm not able to reproduce this on my machine. All of the versions check out, though.

Does this happen randomly, or every time you right click?

[mariansam]

Yes, this happens pretty much randomly. Sometimes I can make a very long graph, but sometimes it crashes after few nodes. The weird thing is that I fount no evidence of self.font in graph.py:656 being None. I added the lines

        print("DOING METRICS")
        print(self.font if self.font is not None else "FONT IS NONE")

before the line metrics = QFontMetrics(self.font) and the end of the output says:

DOING METRICS
<PyQt5.QtGui.QFont object at 0x7f75e6ef4900>
DOING METRICS
<PyQt5.QtGui.QFont object at 0x7f75e6ef4580>
DOING METRICS
<PyQt5.QtGui.QFont object at 0x7f75e6ef43c0>Traceback (most recent call last):
  File "/home/marian/.local/lib/python3.9/site-packages/grafatko/__init__.py", line 291, in mouseReleaseEvent
    pressed_vertices = self.graph.vertices_at_position(self.mouse.get_position())
  File "/home/marian/.local/lib/python3.9/site-packages/grafatko/graph.py", line 939, in vertices_at_position
    if vertex._get_weight_box(self.is_directed()).contains(*position):
  File "/home/marian/.local/lib/python3.9/site-packages/grafatko/graph.py", line 656, in _get_weight_box
    metrics = QFontMetrics(self.font)
TypeError: arguments did not match any overloaded call:
  QFontMetrics(QFont): argument 1 has unexpected type 'NoneType'
  QFontMetrics(QFont, QPaintDevice): argument 1 has unexpected type 'NoneType'
  QFontMetrics(QFontMetrics): argument 1 has unexpected type 'NoneType'

So self.font is not None, but "NoneType TypeError" is still thrown.