set state to blank object on destroy, not null

[Rich-Harris]

fixes #1354. This makes sense in v2 since we're encouraging widespread use of destructuring.

[Conduitry]

Re: my comment on #1354 - is there a different good way of determining whether a component has been deleted?

[Rich-Harris]

Internally we can check for the existence of this._fragment. We toyed with the idea of adding a component.destroyed property that would become true on destroy(), but weren't sure if people actually needed it.

[codecov-io]

Codecov Report

Merging #1365 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1365   +/-   ##
=======================================
  Coverage   91.49%   91.49%           
=======================================
  Files         126      126           
  Lines        4468     4468           
  Branches     1383     1383           
=======================================
  Hits         4088     4088           
  Misses        154      154           
  Partials      226      226

---

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 a78f37d...fd7aced. Read the comment docs.