Ngrams Unable to parse stats.field, not properly escaped?

[danieleguido]

From:
https://impresso-project.ch/app/search/ngrams?sq=CgQIARgCCjQIARACGAoqLDE5ODMtMDEtMzFUMDA6MDA6MDBaIFRPIDIwMTgtMTItMzFUMjM6NTk6NTlaChMIARACGAcgASoJQ29udHJBdG9t&unigrams=ENC%2786","errorMessage":"Unable to parse stats.field: {!tag=tf_stats_fr key=tf_stats_fr sum=true func}termfreq(content_txt_fr,'ENC'86') due to: Expected ',' at position 29 in 'termfreq(content_txt_fr,'ENC'86')'","stackTrace":"SolrError: Unable to parse stats.field: {!tag=tf_stats_fr key=tf_stats_fr sum=true func}termfreq(content_txt_fr,'ENC'86') due to: Expected ',' at position 29 in 'termfreq(content_txt_fr,'ENC'86')