GeezerVison

Calling host() on a sparse array threw:

Invalid argument at index 0
Expected: info->isSparse() == false

host() sizes its buffer from elements(), which already reports the dense shape for a sparse array, so af_get_data_ptr now converts CSR and COO arrays to dense and copies that. CSC to dense is not implemented anywhere, so a CSC array fails with AF_ERR_NOT_SUPPORTED and a message saying to convert to CSR or COO first; the C++ and C docs say the same. Callers who relied on the old error to detect sparse arrays now get data instead, which is worth a line in the release notes. Tests cover the reported case and compare host() against the dense source for CSR and COO; the sparse suite passes on the CPU backend (88 tests). Fixes #3703.