fix a leak with indented heredocs

fix a leak with indented heredocs

With something like

   |print <<~EOF;
   | some data
   |   EOF

it croaks (as it should) with "Indentation ... doesn't match delimiter",
but in that case it leaks the recently malloc()d 'indent' buffer.

The fix is simple.  I've also fixed by code inspection where the code
does 'goto interminable', although I didn't try to reproduce the conditions
where the goto might occur.