Fix empty render in docs and doc build error

[lorenzncode]

Closes #1364

[codecov]

Codecov Report

Merging #1367 (1f4ee77) into master (44ae035) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

❗ Current head 1f4ee77 differs from pull request most recent head 57d815a. Consider uploading reports for the commit 57d815a to get more accurate results

@@            Coverage Diff             @@
##           master    #1367      +/-   ##
==========================================
- Coverage   94.15%   94.10%   -0.06%     
==========================================
  Files          26       26              
  Lines        5611     5611              
  Branches      956      956              
==========================================
- Hits         5283     5280       -3     
- Misses        195      198       +3     
  Partials      133      133              

Impacted Files	Coverage Δ
cadquery/occ_impl/assembly.py	97.27% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[lorenzncode]

I'll revert to the previous version of the assembly doc example. To avoid the cqgi error, the unsupported parameter type can be skipped. Perhaps with a future enhancement cqgi can support additional parameter types.

[jmwright]

Looks good, thanks @lorenzncode

Should we create an issue for adding tuple support to CQGI?

[lorenzncode]

Should we create an issue for adding tuple support to CQGI?

Done, opened #1370

[adam-urbanczyk]

Thanks @lorenzncode !