PSAR fires InvalidOptionError when it should raise InvalidInputError

[smauermann]

Consider following snippet, where I pass arrays of length 1 to ti.psar():

>>> import tulipy as ti
>>> import numpy as np
>>> ti.psar(np.array([3]), np.array([1]),0.2,2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "xxx/lib/python3.7/site-packages/tulipy/__init__.py", line 919, in psar
    return lib.psar([high, low], [acceleration_factor_step, acceleration_factor_maximum])
  File "tulipy/lib/__init__.pyx", line 105, in tulipy.lib._Indicator.__call__
tulipy.lib.InvalidOptionError

To me the error type is confusing, since clearly the inputs do not conform here. Wouldn't it make sense to raise InvalidInputError here?

[cirla]

Probably this code.

Looks like ti_psar_start always returns 1 so the Cython code will raise InvalidOptionError but the tulipy behavior is to silently do nothing with the output.

I'm not sure how to generically implement this, we'd have to special case certain indicators.