You seem to be discounting assets, like taxation power (now, the politicsl consensus necessary for the state to use that power may not exist, but that's unwillingness to use an asset, not lack of assets.)
That’s like marking at 100 a bond trading at 30 while arguing the problem isn’t the asset, it’s buyers’ unwillingness to pay the right price. In any case, potential to raise taxes is like potential to raise prices. It isn’t an asset until it’s signed and producing.
assets, like taxation power
Now we go straight from a misdefinition of "bankruptcy" to outright fabrication of "asset". Each of us may have earning power, for example, but that doesn't make it an asset we can legitimately put on a balance sheet.And taxation power is constrained by the US and IL Constitutions and even US and IL law.
Illinois can currently pay its debts as they come due, so it is currently solvent. It is likely to become insolvent in the future, but that is not the current state.
There's a difference between not having the money to pay debts as they come due (which is insolvency) and just paying late by choice, incompetence, or -- as happens with in some jurisdictions with budget delays -- legal prohibition on using existing funds [0] (none of which are insolvency, though they may be default on the individual debts).
[0] Which, looked at one way, is a subset of choice, since the actors not making the necessary choice to remove the legal roadblock are the political leadership of the state.
It almost certainly can, if it chooses to, but it hasn't been choosing to, if you consider the pension fund distinct from the state.