Only minimal checking of the inputs is done, for performance reasons.
sparse_division_scalar() and sparse_multiplication_scalar() are the most
used ones, as they preserve the default, which is often what you want to do.
sparse_division_scalar() always produces double vectors, regardless of
whether they could be represented as integers or not. Expect when val = 1
as the input is returned unchanged, or val = NA as the input returned will
be NA or the appropiate type. When val = 0 the result contains Inf,
-Inf and NaN, which sparse vectors can't store, so a regular (dense)
double vector is returned.
The other functions return a sparse vector of the same type as x. This
means that when x is a sparse integer vector, val must be a whole number.
Integer overflow in the stored values produces NA with a warning, as it
does for dense integer vectors.
When val is NA or NaN a regular (dense) vector of NA or NaN values
is returned.
Results that sparse double vectors can't store, such as stored values that
are Inf or NaN, or a default value that is NaN, give an error. The
exception is sparse_multiplication_scalar() with val = 0, which keeps
NaN for stored Inf and NaN values, since Inf * 0 is NaN.