HP50 : indefinite integral of '0^x' gives '?' and 0 for '0*x'

[Gil]

Try on the HP50G
'0^X' INTVX (integral of 0^X).

But S (0^X) dX
is equivalent to S (0) dX = Constant,
as the derivative of a constant is equal to 0.

But the HP50G returns '?'.

Besides, if you write directly 0 INTVX (integral of 0),
the calculator returns 0 (instead of Constant).

Somewhat disappointing.

However, the HP50G gives correctly the numerical area (with the command —>NUM, but not with EVAL command) from a to b for the function '0^X': 0, as [b-a] × 0 = 0.

Does another calculator like the Prime, or CASIO/TI gives the expected answers?