Infinite reactivity issue

[JohnCoene]

Having looked at the issue with infinite reactivity I came up with this quick fix.

Note, as I understand it there are two different cases of the infinite reactivity observed in the app.

1. Infinite reactivity can happen on almost any input that is not debounced when changed quickly emough, e.g.: numericInput (probably possible on inputs that are debounced but less likely).

The solution here is to capture the last input and check against that server-side. So we run our loop over all fields updating them all, except for the input that triggered that loop of updates. Thereby avoiding the "input updating itself" and leading to an infinite reactive loop.

https://github.com/blockr-org/blockr/blob/1619358e6e6bd32d59511498cb73b6a82689041e/srcjs/input.js#L1

2. Described in Slider is flickering for filter block  #322 caused by updating generated inputs the list field, namely in the filter. The fix described above does not apply here and we still see the infinite reactive loop.

I can only do this rather ugly hack below to prevent that: if the last input is one of the generated inputs as part of the field we do not update it.

https://github.com/blockr-org/blockr/blob/1619358e6e6bd32d59511498cb73b6a82689041e/R/server.R#L79

Note that I'm really just trying to find a quick fix so we don't encounter that in near-term demos and uses of blockr, I'm well aware that a proper fix is still needed.

@nbenn @DivadNojnarg let me know what you think.

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 77.61%. Comparing base (6994ab0) to head (4306af6).

Files	Patch %	Lines
R/server.R	76.92%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #352      +/-   ##
==========================================
- Coverage   77.62%   77.61%   -0.02%     
==========================================
  Files          19       19              
  Lines        2083     2095      +12     
==========================================
+ Hits         1617     1626       +9     
- Misses        466      469       +3     

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