Fix unterminated expression crashing.

[SolfaMode]

A user-entered string "https://api.github.com/repos/{" used to crash the Scanner. This is fixed now.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.29%. Comparing base (72fb737) to head (79ccee8).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #112      +/-   ##
===========================================
+ Coverage    98.28%   98.29%   +0.01%     
===========================================
  Files           15       15              
  Lines          523      526       +3     
===========================================
+ Hits           514      517       +3     
  Misses           9        9              

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[alexdeem]

Many thanks for this @SolfaMode
I patched in a very minor change to appease SwiftFormat.

I'll get a release out shortly.