CS8619 Null forgiving operator and ternary operator ?:

[FICTURE7]

Version Used:
Visual Studio Community 2019 16.3.5

Steps to Reproduce:

1. Use ternary operator with task whose result can be nullable as follows.

public Task<string?> ThingAsync(int x)
{
    var what0 = Task.FromResult("");
    var what1 = Task.FromResult(default(string));
    if (x == 0)
        return what0!; // No warning.
    return what1;
}

public Task<string?> ThingTernaryAsync(int x)
{
    var what0 = Task.FromResult("");
    var what1 = Task.FromResult(default(string));
    return x == 0 ? what0! : what1; // Warning.
}

Here is the SharpLab link.

Expected Behavior:
No warning in ThingTernaryAsync(int).

Actual Behavior:

Warning	CS8619	Nullability of reference types in value of type 'Task<string>' doesn't match target type 'Task<string?>'.
Warning	CS8619	Nullability of reference types in value of type 'Task<string?>' doesn't match target type 'Task<string>'.

[jcouv]

FYI @cston