HPCC-12036 Warn if floating point indices used when perhaps a range was intended

Signed-off-by: jamienoss <james.noss@lexisnexis.com>
Merge pull request #6446 from jamienoss/issue12036-wrn-on-flt-pnt-indx

HPCC-12036 Warn if floating point indices used when perhaps a range was meant

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>