The script probably specifies web_add_header( "Accept?Encoding", "chunked") and/or web_add_auto_header( "Accept?Encoding", "chunked"). The server responded by sending a message with a response header "Transfer?Encoding: chunked" and response body structured accordingly. The structure of the body returned from the server seems to be invalid.
Troubleshooting
Look in the script for web_add_header( "Accept?Encoding", "chunked") and/or web_add_auto_header( "Accept?Encoding", "chunked"), and comment out or remove these lines.