fix: avoid loading fast-text-encoding if not in browser environment

[modeswitch]

Fixes #626

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[JustinBeckwith]

Thanks for the fix!

[codecov]

Codecov Report

Merging #627 into master will decrease coverage by 0.22%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master     #627      +/-   ##
==========================================
- Coverage   88.47%   88.25%   -0.23%     
==========================================
  Files          18       18              
  Lines         781      783       +2     
  Branches       85       86       +1     
==========================================
  Hits          691      691              
- Misses         79       80       +1     
- Partials       11       12       +1

Impacted Files	Coverage Δ
src/crypto/browser/crypto.ts	11.53% <50%> (-0.97%)	⬇️

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[codecov]

Codecov Report

Merging #627 into master will decrease coverage by 0.22%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master     #627      +/-   ##
==========================================
- Coverage   88.47%   88.25%   -0.23%     
==========================================
  Files          18       18              
  Lines         781      783       +2     
  Branches       85       86       +1     
==========================================
  Hits          691      691              
- Misses         79       80       +1     
- Partials       11       12       +1

Impacted Files	Coverage Δ
src/crypto/browser/crypto.ts	11.53% <50%> (-0.97%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b78f164...ef6f894. Read the comment docs.

[modeswitch]

@JustinBeckwith I see where the coverage dropped, but I'm not sure how to simulate a browser environment without a bunch of extra work. For one line of code that seems excessive?