There seems to be no tree in the list, so the tool crashes.
By catching the access of an empty list, it actually generates
the cells as expected.

This had prevented issue#22 from being fixed

Merge pull request 'Improved placement of power rail vias' (#21) from Sourcerer/lclayout:main into main

Reviewed-on: https://codeberg.org/librecell/lclayout/pulls/21

* instead introduce the `magscale` parameter for `MagicWriter`
* use `magscale` parameter in the tech-file to set the correct scale

This reverts commit f84b5b28.

This reverts commit 60392378.

Dict

This should be changed into an additional magscale parameter in the
.tech file instead