Issues parsing GFF strand "?"

[Rik-149]

I obtained stringtie 2.2.1 through apt-get and there is a possibility this has been fixed in later versions, however I did not find it in the releasenotes.

Stringtie does not seem to be able to parse strands with value "?". GFF spec allows this.

Error parsing strand (?) from GFF line:
NC_042756.1     RefSeq  mRNA    119185  219853  .       ?       .       ID=rna-FKU89_mgp27;Parent=gene-FKU89_mgp27;Dbxref=GeneID:40498719;exception=trans-splicing;gbkey=mRNA;gene=nad5;locus_tag=FKU89_mgp27

The reference file was obtained from https://www.ncbi.nlm.nih.gov/datasets/genome/?taxon=4236 and provided to stringtie using -G option

Thank you for maintaining this tool, I use it often

Edit: upon further investigation, the same happens in version 3.0.0 obtained from github