[3.6.0-rc.1] abort metacommand parameter not optional

[Serbitar]

When you run abort in either a macro or just directly in DWC you get the error

abort
Error: expected an expression

The documentation defines abort as

Abort command

abort <opt-expression>

This causes all nested macros and the current print file (if any) to be terminated. The expression (if present) is converted to a string, which is included in the message presented to the user and written to the log file.

So the expression should be optional. I have not seen any mention of this being changed in the changelog.

Is this a planned change or a bug?