Fixes compilation error with some versions of libstdc++

Some versions of GCC don't expose append_range()/insert_range(), but
when they did, this was b0rked. This patch checks no_range_insertions().

I introduced this compilation error in: 9b3679cc94d853b534cd97d3573e0045d3611dd2
Oops... :-/

Assisted-by: Codex:GPT-5

Signed-off-by: Jesse F. Williamson <jfw@ibm.com>