c06ea02bfd
This PR handles the case where users call the `--sparse-tensor-codegen` pass without sufficiently lowering dense tensors to sparse ones (with passes like `--lower-sparse-ops-to-foreach` and `--lower-sparse-foreach-to-scf` among others). This results in dense tensors having a null `SparseTensorEncodingAttr`, which was originally assumed to be true in the SparseTensor's `ConvertOp` lowering, but is now checked against. This PR closes #177779.