Node: Replace usage of Variant with SumType

[Geod24]

Fixes #281

[codecov]

Codecov Report

Merging #291 (912f6e4) into master (e157571) will decrease coverage by 0.59%.
The diff coverage is 50.00%.

❗ Current head 912f6e4 differs from pull request most recent head d0c691d. Consider uploading reports for the commit d0c691d to get more accurate results

@@            Coverage Diff             @@
##           master     #291      +/-   ##
==========================================
- Coverage   96.03%   95.43%   -0.60%     
==========================================
  Files          28       28              
  Lines        4086     4100      +14     
==========================================
- Hits         3924     3913      -11     
- Misses        162      187      +25     

Impacted Files	Coverage Δ
source/dyaml/node.d	91.13% <50.00%> (-2.61%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e157571...d0c691d. Read the comment docs.

[Geod24]

Green

[Geod24]

It's a requirement to be able to support DIP1000

[Herringway]

Seems good. Just a few things to address.

[Geod24]

@Herringway : Updated

[Geod24]

Except it doesn't work for LDC, and those error messages are really unhelpful.

[Herringway]

it's pretty noisy, but I can see that LDC is deciding that the ubyte[] and SysTime lambdas in that tryMatch are @system for some reason

[Geod24]

@Herringway : The bug is related to inout. I will reduce it and report it upstream, but for now, can we go ahead with the present version ? It ensures that match itself is @safe if the delegates are.