Running assemble_spades.pl produces warning messages

[greatfireball]

Running the script assemble_spades.plstandalone results ins a couple of warnings:

root@1048a032b1ea:/data# assemble_spades.pl --version
Use of uninitialized value $pre in concatenation (.) or string at /opt/chloroExtractor/bin/assemble_spades.pl line 11.
SPAdes v3.10.1
Use of uninitialized value $pre in concatenation (.) or string at /opt/chloroExtractor/bin/assemble_spades.pl line 19.
Use of uninitialized value $pre in concatenation (.) or string at /opt/chloroExtractor/bin/assemble_spades.pl line 20.

The value for $pre should therefore be an empty string instead of undef