chore: Remove unused catch variables

[TrevorBurnham]

Description of changes:

This started as an attempted follow-up for #169 to take advantage of new optimizations available in ES2019. Unfortunately, I couldn't many in this codebase. There are a couple of modernization tweaks in this branch (changing .indexOf(...) > -1 to .includes(...) and replacing .apply with a spread), but the main change I wound up making was just getting rid of unused catch variables:

// Before
try { ... } catch (ex) { ... }

// After
try { ... } catch { ... }

That shaves off a few bytes from the bundle, and it's also a code style improvement IMO, as it makes it clearer that the caught exception is unused. I've configured the no-unused-vars rule to catch that pattern in the future.

If this is approved, I'll submit the same change for cloudscape-design/components, where I expect the bundle size improvement to be more significant.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.78%. Comparing base (54c5ad9) to head (a9a41a1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #170   +/-   ##
=======================================
  Coverage   98.78%   98.78%           
=======================================
  Files          36       36           
  Lines         904      904           
  Branches      255      256    +1     
=======================================
  Hits          893      893           
+ Misses         11       10    -1     
- Partials        0        1    +1     

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