nbgv@v0.3 System.NullReferenceException: Object reference not set to an instance of an object.

[edwardskrod]

I've been hitting this exception since I upgraded to aarnott/nbgv@v0.3

https://github.com/microsoft/github-actions-for-desktop-apps/blob/master/.github/workflows/ci.yml

Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at LibGit2Sharp.Core.Proxy.git_commit_tree_id(ObjectHandle obj)
at LibGit2Sharp.Commit.<>c__DisplayClass11_0.<.ctor>b__0(ObjectHandle obj)
at LibGit2Sharp.Core.GitObjectLazyGroup.<>c__DisplayClass3_01.<Singleton>b__0() at System.Lazy1.ViaFactory(LazyThreadSafetyMode mode)
at System.Lazy1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor) at System.Lazy1.CreateValue()
at Nerdbank.GitVersioning.VersionFile.GetVersion(Commit commit, String repoRelativeProjectDirectory) in D:\a\1\s\src\NerdBank.GitVersioning\VersionFile.cs:line 52
at Nerdbank.GitVersioning.GitExtensions.CommitMatchesVersion(Commit commit, SemanticVersion expectedVersion, Position comparisonPrecision, String repoRelativeProjectDirectory) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 450
at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary2 heights, Func2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 676
at System.Linq.Enumerable.Max[TSource](IEnumerable1 source, Func2 selector)
at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary2 heights, Func2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
at Nerdbank.GitVersioning.GitExtensions.GetVersionHeight(Commit commit, String repoRelativeProjectDirectory, Version baseVersion) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 65
at Nerdbank.GitVersioning.VersionOracle..ctor(String projectDirectory, Repository repo, Commit head, ICloudBuild cloudBuild, Nullable`1 overrideVersionHeightOffset, String projectPathRelativeToGitRepoRoot) in D:\a\1\s\src\NerdBank.GitVersioning\VersionOracle.cs:line 86
at Nerdbank.GitVersioning.Tool.Program.OnGetVersionCommand(String projectPath, String format, String singleVariable, String versionOrRef) in D:\a\1\s\src\nbgv\Program.cs:line 305
at Nerdbank.GitVersioning.Tool.Program.MainInner(String[] args) in D:\a\1\s\src\nbgv\Program.cs:line 149
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Nerdbank.GitVersioning.Tool.Program.Main(String[] args) in D:\a\1\s\src\nbgv\Program.cs:line 64
##[error]The process 'C:\Users\runneradmin.dotnet\tools\nbgv.exe' failed with exit code 3762504530

[edwardskrod]

The problem was that I had the fetch-depth.

Checkout requirements
Git history based versioning tools rely on history being included in the clone. actions/checkout@v1 does this by default. But if you're using actions/checkout@v2 you'll need to specify deep clone:

• uses: actions/checkout@v2
  with:
  fetch-depth: 0 # avoid shallow clone so nbgv can do its work.