[BUG] Projects cannot be viewed if the project owner no longer exists

[dragon-fire-fly]

Describe the bug When users are deleted, their projects still appear on the "project overview" page but a NoReverseMatch exception occurs as the project owner cannot be found.

To Reproduce Steps to reproduce the behavior:

1. Go to 'Project Overview'
2. Click on a project where the owner no longer exists
3. See error

Expected behavior Projects should still be able to be viewed even if the project owner no longer exists

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu 22.04
• Browser: Chrome
• Version: 108.0

Additional context The code suspected to be responsible for the reverse lookup error:

        <div class="col-md-8 offset-md-3">
            <p><strong>Title:</strong> {{ project.title }}</p>
            <p><strong>Description:</strong> {{ project.description }}</p>
            <p><strong>Project Owner:</strong><a href="{% url 'app_home:profile-detail-view' project.user.values.0.username %}">{{ project.user.values.0.username }}</a></p>
            <p><strong>Programming Languages:</strong> 
                {% for language in project.p_language.values %}
                {{ language.language }}
                {% endfor %}</p>
        </div>
    </div>```

[dragon-fire-fly]

Firstly, the model was updated to allow the user field to be blank.

class Project(models.Model):
    user = models.ManyToManyField(User, blank=True)
    p_language = models.ManyToManyField(ProgrammingLanguage)
    title = models.CharField(
        help_text="What is the title for your project?", max_length=100
    )
    description = models.TextField(
        help_text="Enter your project description here", blank=True, null=True
    )

    def __str__(self):
        return f"<Project name: {self.title}>"

Next, an if statement was added to check whether there is a user associated with the project. If so, the user is displayed and a link to that user's profile is provided. If not. the user is informed that the selected project does not have an owner.

    <div class="row">
        <div class="col-md-8 offset-md-3">
            <p><strong>Title:</strong> {{ project.title }}</p>
            <p><strong>Description:</strong> {{ project.description }}</p>
            {% if project.user.values.0.username %}
            <p><strong>Project Owner:</strong><a href="{% url 'app_home:profile-detail-view' project.user.values.0.username %}">{{ project.user.values.0.username }}</a></p>
            {% else %}
            <p><strong>Project Owner:</strong>This project no longer has an owner</p>
            {% endif %}
            <p><strong>Programming Languages:</strong> 
                {% for language in project.p_language.values %}
                {{ language.language }}
                {% endfor %}</p>
        </div>
    </div>