How severe should the consequences of the assertion be?
Either "stop", "warning", "message", or "none".
.xname
Not intended to be used directly.
Value
is_raster wraps is.raster, providing more
information on failure. is_a_raster returns TRUE if the
input is raster and scalar. The assert_* functions return nothing but
throw an error if the corresponding is_* function returns
FALSE.