Cannot read Gzip file in JalviewJS

When reading a gzipped file in jalview.io.FileParse.parse(Object, DataSourceType) occurs in JalviewJS, the contents of the file are obtained as a byte array. Doing the obvious thing to check whether this is a GzipStream (e.g. doing

      if (bytes != null)
      {
        // this will be from JavaScript
        inFile = file;
        // dataIn = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(bytes))); // this line changed ...
        try
        {
          dataIn = checkForGzipStream(new ByteArrayInputStream(bytes)); // ... to this (requires try)
        } catch (Exception e)
        {
          e.printStackTrace();
        }
        dataName = fileStr;
      }

)
results in the following error in JalviewJS:

TypeError: this.$in.read$BA$I$I is not a function
@swingjs/j2s/java/io/InputStreamReader.js:50:22
@swingjs/j2s/java/io/BufferedReader.js:56:12
@swingjs/j2s/java/io/BufferedReader.js:68:10
@swingjs/j2s/jalview/io/FileParse.js:112:8
@swingjs/j2s/jalview/io/FileParse.js:103:46
@swingjs/j2s/jalview/io/FileParse.js:210:56
@swingjs/j2s/jalview/io/FileParse.js:197:54
J2S.LoadClazz/Clazz.new_@http://localhost:9001/swingjs/swingjs2.js:14562:19
@swingjs/j2s/jalview/io/IdentifyFile.js:17:14
@swingjs/j2s/jalview/io/FileLoader.js:122:35
@swingjs/j2s/java/lang/Thread.js:144:13
ff@swingjs/j2s/swingjs/JSToolkit.js:160:8
    
Error whilst identifying ./test2.fa.gz
java.io.IOException: Failed to read data from source: UNINITIALISED SOURCE
anonymous.anonymous(Unknown Source)
lost.missing(Unknown Source)
Exception whilst opening file './test2.fa.gz
jalview.io.FileFormatException: Failed to read data from source: UNINITIALISED SOURCE
anonymous.anonymous(Unknown Source)

This appears to occur when creating the ByteArrayInputStream from the byte array. Unfortunately this needs to be done to create a GZIPInputStream used to gunzip the file contents.

Likely to be fixed by SwingJS implementing this.$in.read$BA$I$I which I think is BufferedReader.read(.,.,.)