Linter fixes

[benjamincburns]

Description

In order to fix #3632, I'm planning on doing some work to refactor the transaction execution flow. When I got started on that I noticed a bunch of linter errors when running npm test. These make it hard to check that my changes haven't broken anything, so I'm submitting a PR to fix them.

Note that this doesn't fix the linter issues in web3-core-method pertaining to deeply nested blocks. Those will be fixed in the PR for #3632.

Note that some tests appear to be failing on my machine when I run npm run test:unit and npm run test:cov. These tests were failing in 1.x before I made this change.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run dtslint with success and extended the tests and types if necessary.
• I ran npm run test:unit with success.
• I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• I ran npm run build and tested dist/web3.min.js in a browser.
• I have tested my code on the live network. (N/A - I'm not introducing new logic changes - it passes all automated client tests)
• I have checked the Deploy Preview and it looks correct.
• I have updated the CHANGELOG.md file in the root folder. (N/A - I'm not introducing new logic changes)

[benjamincburns]

Update: if I switch back to node v10.21.0, tests pass just fine.

[benjamincburns]

I ran npm run build and tested dist/web3.min.js in a browser.

I'd like to check this off, but is there an existing test harness? The application that I'm working on doesn't run in the browser.

If the e2e_browsers CI test is passing, I'd assume we can call this good?

[coveralls]

Coverage increased (+0.006%) to 90.26% when pulling 597155f on benjamincburns:linter-fixes into 9239f6b on ethereum:1.x.

[GregTheGreek]

The netlify/web3-staging/deploy-preview as a part of the CI actually runs web3 in the browser, so it seems to work!