fix: consistent subscriber values

[tivac]

Previously if you called the .subscribe() method on a ComponentTree instance before the statechart had been processed the return value would be false. This meant that subscribers would have to add checks to do anything against the returned value, since they couldn't depend on the .matches/.hasTag/.broadcast APIs existing.

This change fixes that, and ensures that even if the statechart hasn't been walked yet the initial value stored has all the expected APIs, along with a reasonable value for the tree property of []. There isn't a great fallback value for .state at this time though.

[changeset-bot]

🦋 Changeset detected

Latest commit: 32fdeb8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
xstate-component-tree	Major

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[codecov-commenter]

Codecov Report

Merging #69 (32fdeb8) into main (44775e0) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #69   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          573       580    +7     
=========================================
+ Hits           573       580    +7     

Impacted Files	Coverage Δ
src/component-tree.js	100.00% <100.00%> (ø)

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