frontend : unable to visualize past submissions (javascript error)

[lsignac]

Describe the bug
students can not access old submissions, due to a Javascript Error.

INGInious installation details

• Version: INGInious @ git+https://github.com/UCL-INGI/INGInious.git@6e14ae8edb65b0ce18059863655659ba9efea129
• Containers version (if applicable) [e.g. the git hash]

To Reproduce
Steps to reproduce the behavior:

1. Go to A task and submit something
2. Click on the left on your old submission
3. The submission does not appear

Expected behavior
The submission should appear in the codemirror editor.

The Javascript error is raised in codemirror (minified) code :

Uncaught TypeError: e.split is not a function
    at Bl (codemirror.js:3:106416)
    at va.splitLines (codemirror.js:3:127125)
    at va.<anonymous> (codemirror.js:3:119630)
    at va.setValue (codemirror.js:3:53793)
    at Do.setValue (codemirror.js:3:160479)
    at load_input_code (task.js:740:30)
    at load_input (task.js:732:52)
    at Object.<anonymous> (task.js:685:17)
    at u (jquery.min.js:2:27457)
    at Object.fireWith [as resolveWith] (jquery.min.js:2:28202)

The line Bl (codemirror.js:3:106416) is return e.split(/\r\n?|\n/)
e should contain the submission code. Instead, e is an Array whose first and only value is the submission code.
e is ['def fn():\r\n...'] instead of 'def fn():\r\n...'.

Looking in the call stack I looked at Object.<anonymous> (task.js:685:17) :

function loadOldSubmissionInput(id, with_feedback)
{
    if(loadingSomething)
        return;

    blurTaskForm();
    resetAlerts();
    displayTaskInputLoadingAlert();
    
    var url = $('form#task').attr("action");
    jQuery.post(url, {"@action": "load_submission_input", "submissionid": id}, null, "json")
        .done(function(data)
        {
            if("status" in data && data['status'] == "ok" && "input" in data)
            {
                updateMainTags(data);
                unblurTaskForm();
                load_input(id, data['input']);
                if(with_feedback) // load feedback in second place as it may affect the input
                    loadOldFeedback(data);
            }
            else
            {
                displayTaskInputErrorAlert();
                unblurTaskForm();
            }
        }).fail(function()
        {
            displayTaskInputErrorAlert();
            unblurTaskForm();
        });
}

Using the chrome debugger, I saw that data['input']['sub01'] (sub01 is the name of the only subproblem of my task) is an Array. I think it should be a string. I added this line
data['input']['sub01'] = data['input']['sub01'][0]; just before load_input(id, data['input']);
Everything works fine !

Sure there is a better fix (may be the issue is in the chunks stored in the database...?), and I would like to know if I am the only one facing this issue