Where state law holds that a particular offense is non-existent, but a defendant has a conviction for the non-existent offense, and a federal sentencing court seeks to rely on the offense to enhance a sentence under the Armed Career Criminal Act (ACCA), is the defendant's challenge to the court's reliance on that conviction an impermissible collateral attack?

Where state law holds that a particular offense is non-existent, but a defendant has a conviction for the non-existent offense, and a federal sentencing court seeks to rely on the offense to enhance a sentence under the Armed Career Criminal Act (ACCA), is the defendant's challenge to the court's reliance on that conviction an impermissible collateral attack?