Did the Court of Appeals err in denying the Petitioner a certificate of appealability on his constitutional claim related to structural error and/or ineffective assistance of counsel in the mercy phase of his bifurcated murder trial, when counsel made no argument for mercy on his behalf, and when counsel failed to inform the jury of available mitigating evidence?

Did the Court of Appeals err in denying the Petitioner a certificate of appealability on his constitutional claim related to structural error and/or ineffective assistance of counsel in the mercy phase of his bifurcated murder trial, when counsel made no argument for mercy on his behalf, and when counsel failed to inform the jury of available mitigating evidence? i