eval '`' reports error but $? is still 0

[Clark Wang]

See the following example (with 5.2.15):

bash-5.2$ PS1='$? >> '
0 >> eval '`'
bash: unexpected EOF while looking for matching ``'
0 >>        <-- press ENTER
2 >>        <-- now $? is 2


It looks like the failed eval '`' is still waiting for some input?