fix: alphaNumeric all chars banned

[xDivisionByZerox]

Created in relation to #518.

• remove additional if check against options argument
• throw if no characters to pick from are available
• activate test case

[codecov]

Codecov Report

Merging #550 (e6515c9) into main (5a15c40) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head e6515c9 differs from pull request most recent head b837232. Consider uploading reports for the commit b837232 to get more accurate results

@@           Coverage Diff           @@
##             main     #550   +/-   ##
=======================================
  Coverage   99.33%   99.33%           
=======================================
  Files        1920     1920           
  Lines      176482   176489    +7     
  Branches      905      908    +3     
=======================================
+ Hits       175302   175309    +7     
  Misses       1124     1124           
  Partials       56       56           

Impacted Files	Coverage Δ
src/random.ts	99.22% <100.00%> (+<0.01%)	⬆️
src/helpers.ts	99.10% <0.00%> (-0.03%)	⬇️
src/iban.ts	100.00% <0.00%> (ø)