Ensure safe access of output guards against missing value property

[jeskew]

Resolves #13160

Safe dereference of a module output (mod.outputs.?foo) is currently written to guard against conditional outputs with a false condition (i.e., it would be equivalent to writing mod.outputs.?foo.value if Bicep didn't automatically inject the .value into module output reference expressions). It currently doesn't guard against outputs whose value is null (which will cause the ARM engine to omit the .value property).

This PR updates the expression converter to make mod.outputs.?foo compile to something like [tryGet(tryGet(reference('mod').outputs, 'foo'), 'value')] to ensure both cases described above evaluate to null when evaluated by the ARM engine.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 7730544761)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 7730544761

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 7730544761"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 7730544761

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 7730544761"

[github-actions]

Test Results

    66 files   -     33      66 suites   - 33   24m 41s ⏱️ - 23m 12s
11 009 tests  -     20  11 009 ✅  -     20  0 💤 ±0  0 ❌ ±0 
25 908 runs   - 12 950  25 908 ✅  - 12 950  0 💤 ±0  0 ❌ ±0 

Results for commit d603aac. ± Comparison against base commit 68ce409.

[shenglol]