The qm_data is HTML, not JSON. The <doctype> is the header on an HTML file. The JSON importer is producing the message because it does not understand HTML.
The JSON may be embedded in the HTML, or there may be a better rest api to get just the JSON data without an extra wrapper.
Ideally the rest api will return bare JSON. If necessary, you can write some sort of pattern matching/regex/substring JSL to dig the JSON out of the HTML.
use
write(qm_data); // if really long, use: write(left(qm_data,1000) );
and look at the log to see what you received.
Craige