feat: throw error for invalid extended input

[peaceiris]

• test: Add invalid case

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 99.20%. Comparing base (da2d546) to head (28797ce).
⚠️ Report is 231 commits behind head on main.

Files with missing lines	Patch %	Lines
src/get-url.ts	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #387      +/-   ##
===========================================
- Coverage   100.00%   99.20%   -0.80%     
===========================================
  Files            6        6              
  Lines          124      126       +2     
  Branches        14       15       +1     
===========================================
+ Hits           124      125       +1     
- Misses           0        1       +1     

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