assembly error for single read R1

[sekhwal]

I have aligned a single-read R1 file with a virus genome using bwa. Next step, I am extracting mapped reads from this bam file. I am following these steps.

samtools fastq -F 260 -@ 8 S1_sotred.bam | gzip > S1_mapped.fastq.gz

unicycler -t 8 -s S1_mapped.fastq.gz -o unicycler_S1

However, Unicycler was not able to make any assembly. Please suggest any solution.