Why can't i COPY from an XHR response???

in FF devtools, i'm debugging my network requests. but it is NOT POSSIBLE to copy a specific number of error messages (like "the first three lines"). the selection deselects instantly, spamming cmd-c does NOT copy the selected text, right click only offers "copy (one) value" or "copy all" which is ALL, including miles of stacktraces which i don't want to copy. it behaves like it's constantly being updated, but it's a one-off request and displaying the results. there is no need to unselect

this is infuriating. why is it like this?? PLEASE change it (if there is somebody here who can?)