Samtools Index: Chromosome Blocks not Continuous
samtools sort blasted_SRR6649368.bam -o sorted_SRR6649368.bam -n

These error messages indicate that the reads are not sorted by coordinate — in particular, that the reads mapped to ScdB1pO_646;HRSCAF=880 are not all together, and that the reads at positions 11159020 &lt; 11158717 are not sorted by position on their chromosome.
This is because samtools sort -n has been used to sort the reads by name instead. Remove -n to sort by position, which is what is needed to prepare a BAM file for indexing with samtools index.