Fix for fatal exception on targetScope with variable value

[anthony-c-martin]

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Fixes #1817

[codecov-io]

Codecov Report

Merging #1825 (7d32c52) into main (fb1a053) will increase coverage by 0.37%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1825      +/-   ##
==========================================
+ Coverage   95.03%   95.40%   +0.37%     
==========================================
  Files         371      367       -4     
  Lines       21671    21525     -146     
  Branches       15        0      -15     
==========================================
- Hits        20594    20537      -57     
+ Misses       1077      988      -89     

Flag	Coverage Δ
dotnet	95.40% <100.00%> (-0.07%)	⬇️
typescript	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/Bicep.Core.IntegrationTests/ScenarioTests.cs	100.00% <100.00%> (ø)
src/Bicep.Core/TypeSystem/CyclicCheckVisitor.cs	100.00% <100.00%> (+3.70%)	⬆️
.../Bicep.Core.UnitTests/Assertions/BaselineHelper.cs	63.63% <0.00%> (-15.91%)	⬇️
src/Bicep.Core.UnitTests/Utils/CompilerFlags.cs	20.00% <0.00%> (-13.34%)	⬇️
...cep.Core.UnitTests/FileSystem/FileResolverTests.cs	88.23% <0.00%> (-8.83%)	⬇️
src/Bicep.Core/FileSystem/PathHelper.cs	96.15% <0.00%> (-3.85%)	⬇️
src/Bicep.Core.UnitTests/Utils/OutputHelper.cs	96.55% <0.00%> (-3.45%)	⬇️
...Bicep.Core.UnitTests/FileSystem/PathHelperTests.cs	100.00% <0.00%> (ø)
src/vscode-bicep/src/utils/logger.ts
src/vscode-bicep/src/extension.ts
... and 2 more

[majastrz]