Overflow error on selecting text color for titles

[Danial Behzadi]

Steps to reproduce:
1. Open a new project.
2. Add a title layer.
3. Insert some text.
4. Select text and click on "Text color" button.
5. Pick Red color.
6. Click "Select" button.

Error text:

Missing soft dependency:
- GSound not found on the system
    -> enables sound notifications when rendering is complete
Traceback (most recent call last):
  File "/usr/lib/x86_64-linux-gnu/pitivi/python/pitivi/titleeditor.py", line 234, in _createCb
    assert source.set_child_property("color", FOREGROUND_DEFAULT_COLOR)
OverflowError: 4294967295 not in range -2147483648 to 2147483647
Traceback (most recent call last):
  File "/usr/lib/x86_64-linux-gnu/pitivi/python/pitivi/titleeditor.py", line 137, in _frontTextColorButtonCb
    self._setChildProperty("color", color)
  File "/usr/lib/x86_64-linux-gnu/pitivi/python/pitivi/titleeditor.py", line 123, in _setChildProperty
    assert self.source.set_child_property(name, value)
OverflowError: 4288937984 not in range -2147483648 to 2147483647

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: pitivi 0.999-1.1ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-17.21-generic 5.4.22
Uname: Linux 5.4.0-17-generic x86_64
ApportVersion: 2.20.11-0ubuntu18
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Mar 9 19:48:37 2020
InstallationDate: Installed on 2019-11-01 (128 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
SourcePackage: pitivi
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.