Remove unnecessary condition

[sweetliquid]

For extraReducers, when it is a function it will not be undefined, when it is undefined we defined a default value for it. Therefore, the judment of undefined is redundant :)

redux-toolkit/src/createSlice.ts

Lines 257 to 266 in d5f1b65

	const [
	extraReducers = {},
	actionMatchers = [],
	defaultCaseReducer = undefined
	] =
	typeof options.extraReducers === 'undefined'
	? []
	: typeof options.extraReducers === 'function'
	? executeReducerBuilderCallback(options.extraReducers)
	: [options.extraReducers]

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[juzhiyuan]

If options.extraReducers === undefined, then the result would be [undefined], right?

[phryneas]

It's a little "wrap-your-head-around" with this.

for options.extraReducers === undefined, this would result in

 const [ 
   extraReducers = {}, 
   actionMatchers = [], 
   defaultCaseReducer = undefined 
 ] = [undefined]

which would then take on the default value of extraReducers = {} at desctructuring.

So yeah, I believe the PR is correct, but I'd like a second opinion here @markerikson or @msutkowski

[markerikson]

Let's go with it.

[markerikson]

Eh, this shoulda gone to master. manually merging back locally.