Fix common lsp panics

[seanyoung]

These lsp crashes are concurrency issues, so writing tests from them is hard.

If we could hand-craft lsp json-rpc messages then this would be easier, but we only test the extension by controlling vscode.

[seanyoung]

Cc @chioni16

[codecov[bot]]

Codecov Report

Merging #1575 (e482236) into main (aaceeb9) will increase coverage by 0.03%. The diff coverage is 83.22%.

@@            Coverage Diff             @@
##             main    #1575      +/-   ##
==========================================
+ Coverage   87.41%   87.45%   +0.03%     
==========================================
  Files         133      133              
  Lines       64133    64138       +5     
==========================================
+ Hits        56063    56091      +28     
+ Misses       8070     8047      -23     

Files	Coverage Δ
src/abi/polkadot.rs	97.75% <100.00%> (ø)
src/bin/solang.rs	67.41% <100.00%> (ø)
src/codegen/cfg.rs	94.02% <100.00%> (ø)
src/codegen/events/polkadot.rs	100.00% <100.00%> (ø)
src/codegen/solana_accounts/account_collection.rs	95.84% <100.00%> (ø)
src/codegen/solana_accounts/account_management.rs	98.68% <100.00%> (ø)
src/codegen/yul/mod.rs	100.00% <100.00%> (ø)
src/emit/polkadot/mod.rs	100.00% <100.00%> (ø)
src/emit/polkadot/target.rs	97.88% <100.00%> (ø)
src/emit/solana/mod.rs	100.00% <100.00%> (ø)
... and 16 more

[seanyoung]

There many warnings of lines not covered by tests in this PR. I'm overlooking them by now, but we should be more careful with them.

I agree. I have added some tests for those.