unable to generate output file - pass chromsome

[complexgenome]

I'd like to generate output file for each chromosome.
I get error as:

Error executing process > 'check (1)'

Caused by:
Missing output file(s) CHRScript_2e1c74ba$_runScript_closure1$_closure3@498c535d.lancet.vcf expected by process check (1)

Below is the code:

process check {
debug true

input:
    val chromosome

output: 

publishDir '/sc/arion/projects/nextflow_pipeline/', mode:'copy'
path("CHR"+{chromosome}+".lancet.vcf")

script:

"""
echo "hello" >  "CHR"${chromosome}".lancet.vcf"
"""

}
workflow {

chr=Channel.of( 1..22, 'X', 'Y' )
check(chr)
}

How do I capture output file name using val chromosome?

I have tried the following but failed:

path(st)
script:
st="CHR"+{chromsome}+".lancet.vcf"