Functionality tested: 'append' command line typed: 'append 123 f/2600' and 'append 123 f/2500' Expecting an error message to be reported to users, however, the system accepts this invalid time input  <!--session: 1604044864306-99c301af-2488-4ea3-8d13-ccce34985a78-->
Functionality tested: 'append'
command line typed: 'append 123 f/2600' and
'append 123 f/2500'
Expecting an error message to be reported to users, however, the system accepts this invalid time input
