Workflow crashes when hi-c read input uses dash before read2

[mahesh-panchal]

The assembly parameters input file should be formatted like:

hic:
  - read1: '/path/to/data'
    read2: '/path/to/data'

but when a user formats the yml like:

hic:
  - read1: '/path/to/data'
  - read2: '/path/to/data'

Then the workflow complains about a null input to read2.

There is a bash snippet to auto-generate the yml input written into the assembly_parameters.yml, but this can easily be missed.