fix: trying to access an undefined object in swaps review quote compo…

[jclancy93]

Description

Fixes the two errors with trade and decimals being undefined that have been causing crashes starting around the 12.1/12.2 release. I was unable to find the root cause of this issue. Variables in the redux store seem to return as undefined, which leads me to think it might be some sort of redux race condition. The lowest common denominator of this error seems to be that getUsedQuote selector in the ReviewQuote component. I have added an additional condition to the render guard in the parent component prepare-swaps-page to prevent these errors

Related issues

MMS-1569

Manual testing steps

1. Open Swaps Page
2. Enter swap amount
3. Edit to token and amount rapidly multiple times
4. Page should not crash

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[github-actions]

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[martahj]

Two questions, possibly not worth digging into right now but things we could consider trying to straighten out in the future:
(1) What's the reason usedQuote may not exist if numberOfQuotes > 0?
(2) Is numberOfQuotes > 0 adding anything here or would we just want to use the presence/absence of usedQuote?

[jclancy93]

Yea for sure, good questions:

1.

This is what I touched on a bit in the PR description usedQuote is derived from getSelectedQuote or getTopQuote, which both use a key to access the quotes object selectedAggId or topAggId. After many changes, there is a single or a couple of render cycles where this is quotes are defined, but usedQuote is not. usedQuote should never be undefined if quotes are defined, but that does not seem to be true always, which is the root cause of this bug. I tried finding out why, but it took me deep into the extension redux setup, which I'm not too familiar with. That's why I opted for a more bandaid fix like this

2.

I think we could probably remove the length check here, but since the checks accomplish similar things to usedQuote and I'd rather minimize the changes required for the PR, I decided to keep it in. If you think it's worth keeping the checks simpler, I can try it out though!

[martahj]

Let's keep it in for now - no harm in it 🤷

[infiniteflower]

Tested, LGTM

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[metamaskbot]

Builds ready [7f128cf]

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Page Load Metrics (2095 ± 140 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	301	2573	1886	571	274
		domContentLoaded	1593	2565	2067	295	142
		load	1640	2570	2095	291	140
		domInteractive	23	114	49	24	12

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• ui: 51 Bytes (0.00%)
• common: 0 Bytes (0.00%)