_propagate_n0n2_srw() not calling PropagElecField() when n2 == 0

[moellep]

https://github.com/radiasoft/rslaser/blob/7edbf2888c24272ac1eba3d06a10eeeba9b521bc/rslaser/optics/crystal.py#L431

In crystal.py _propagate_n0n2_srw() if n2 is 0, it creates an optBL container structure, but then does nothing with it. It looks like the call to srwlib.srwl.PropagElecField(thisSlice.wfr, optBL) should be out-dented a level so the optBL is propagated for all values of n2.

[bruhwiler]

@k-wolfinger -- please have a look. It would be worth checking the other prop_type methods as well.

Also, we should check for n2<0 and throw an exception in that case.

[k-wolfinger]

• _propagate_n0n2_lct is fine
• _propagate_abcd_lct is fine
• _propagate_n0n2_srw:
  • Had to out-dent srwlib.srwl.PropagElecField(thisSlice.wfr, optBL) a level

Testing changes and adding a check for n2<0 now

[k-wolfinger]

Added check for n2<0 and tested changes. Tests all passing.