Add infinite loop prevention

[ghengeveld]

Description

This adds a mechanism that detects 'infinite' loops, and throws an error if that happens. This makes sure that if a user were to inadvertently create a loop, for example by defining promiseFn inline, the browser won't hang but the app will crash instead.

This fixes #34

Checklist

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• Implementation for both <Async> and useAsync()
• Added / updated the unit tests
• Added / updated the documentation

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Codecov Report

Merging #165 into next will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             next     #165   +/-   ##
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  Coverage   98.62%   98.62%           
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  Files           9        9           
  Lines         436      436           
  Branches      150      150           
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  Hits          430      430           
  Misses          6        6

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[phryneas]

Besides that, it looks good to me 👍

[phryneas]

I'd use useRefinstead of useState here and keep preventLoop in a ref, as it is not really application state. But that's more a thing of semantics and will not affect anything.

Maybe move it out in a custom hook like this:

function useLoopPreventer() {
    const preventLoop = useRef();
    if (!preventLoop.current) { 
        preventLoop.current = loopPreventer(); 
    }
    return preventLoop.current;
}

[ghengeveld]

It can't be a hook, because <Async> is backwards compatible to React 16.3 which doesn't support hooks.

[ghengeveld]

The reason I used useState is for its lazy initial value. I give it a function that will only be invoked once, which is exactly what I want. It can be done with useRef but requires more code and doesn't take a resolver function for the initial value, so we'd be creating a new function each render, which we don't need.