Prefer await to then tests

[brettz9]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• New rule
• Changes an existing rule
• Add autofixing to a rule
• Other, please explain:

What changes did you make? (Give an overview)

• Linting: Fix as per current prettier
• Testing: Fix test (was not parsing)
• Testing: Fix test (missing an error message)

The need for these changes was introduced in 6378bb9

I might suggest enabling Travis on PRs: https://github.com/apps/travis-ci so as to be able to catch test and linting regressions before PRs are merged.

While the linting fix and one of the test fixes were clear as to resolution, in the case of:

-    'a = async () => (try { await something() } catch { somethingElse() })',

+    `a = async () => {
+      try { await something() } catch (error) { somethingElse() }
+    }`,

I had two reasons for my changes:

1. try cannot be within (), as it requires an expression, and try is a statement.
2. If you want to use optionally bound catch (i.e., with no (error)), the test would need to be changed to the following (I can change it to this if desired, but didn't want to overcomplicate things if this wasn't needed by the test):

    {
      code: `a = async () => {
      try { await something() } catch { somethingElse() }
    }`,
      parserOptions: {
        ecmaVersion: 2019
      }
    }

I think this should probably be settled before #184 may be assessed (then I can rebase that on this).

[brettz9]

Closing as incorporated within merged #184 . Thanks for the merge!