fix: early exit for top-level undefined errors

[hstove]

• Fixes Unexpected error for undefined variable #6370

This PR implements a fix for throwing the expected error (UndefinedVariable) instead of a CostError when the contract contains a top-level variable that isn't defined.

[kantai]

Is this change in error types consensus-breaking? I think it would be good to add a convincing test that demonstrates that it is not consensus breaking.

It should be possible to setup a test kind of like this one (https://github.com/stacks-network/stacks-core/blob/master/stackslib/src/chainstate/nakamoto/coordinator/tests.rs#L880) where instead of producing a contract which uses block-info, we have a contract that exercises the error. Then, after the block is processed, the test can assert that the transaction is processed (or not processed) with a given return value, the evaluated cost matches some exact number, and maybe even that the block hash matches an exact hash. Then we could run the test in develop (with a local cherry-pick) and on this branch and ensure it passes in both places.

[hstove]

@kantai @jferrant mind re-reviewing? I had a conflict that needed to be fixed.

[codecov]

Codecov Report

❌ Patch coverage is 20.65217% with 73 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.33%. Comparing base (c1a989f) to head (424ec11).
⚠️ Report is 11 commits behind head on develop.

Files with missing lines	Patch %	Lines
stacks-node/src/tests/signer/v0.rs	0.00%	64 Missing ⚠️
stackslib/src/chainstate/stacks/miner.rs	0.00%	7 Missing ⚠️
stackslib/src/clarity_vm/tests/analysis_costs.rs	83.33%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #6448      +/-   ##
===========================================
+ Coverage    78.86%   79.33%   +0.46%     
===========================================
  Files          558      558              
  Lines       343239   343329      +90     
===========================================
+ Hits        270699   272372    +1673     
+ Misses       72540    70957    -1583     

Files with missing lines	Coverage Δ
clarity/src/vm/analysis/type_checker/v2_05/mod.rs	90.45% <100.00%> (+0.04%)	⬆️
clarity/src/vm/analysis/type_checker/v2_1/mod.rs	90.37% <100.00%> (+0.02%)	⬆️
...c/vm/analysis/type_checker/v2_1/tests/contracts.rs	95.87% <100.00%> (+<0.01%)	⬆️
stackslib/src/clarity_vm/tests/analysis_costs.rs	98.14% <83.33%> (-0.88%)	⬇️
stackslib/src/chainstate/stacks/miner.rs	80.36% <0.00%> (+3.73%)	⬆️
stacks-node/src/tests/signer/v0.rs	0.46% <0.00%> (-4.15%)	⬇️

... and 95 files with indirect coverage changes

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[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.