Passing check_parameters through minimize and tg.grad raises TypeError

[Michal-Novomestsky]

Addresses #1743

[ricardoV94]

Sorry this is actually masking an error. A ScalarFromTensor should have a scalar gradient, and therefore tensor_from_scalar is correct

[Michal-Novomestsky]

Sorry this is actually masking an error. A ScalarFromTensor should have a scalar gradient, and therefore tensor_from_scalar is correct

Sorry I'm not quite following - do you mean that there is a deeper bug unrelated to this code, and fixing that bug means that this PR is unecessary?

[ricardoV94]

There's a deeper bug, your fix is making it.
Assumptions:

1. This Op can only be called in a Scalar, it always outputs a Tensor
2. Any gradient expression coming in reverse_mode (output_gradients) must have the same type as the output, i.e, be a Tensor
3. It should always be safe and correct to call ScalarFromTensor on this output.

Point 2. is the crux. Some Op gradient is returning a scalar when it should return a tensor, or some invalid graph manipulation was done. Need to find what variable is creating that tensor output gradient. Can you check if the variable has a traceback in var.tag?

[ricardoV94]

Do you have a MWE that reproduces the bug?