Trying to build without CMake installed gives a confusing error message

Namely

.\build.libgit2.ps1 14
Index was outside the bounds of the array.
At C:\source\github.com\libgit2sharp\libgit2sharp.nativebinaries\build.libgit2.ps1:71 char:16
+     $cmake = @(Get-Command cmake.exe)[0] 2>$null
+                ~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (:) [], IndexOutOfRangeException
    + FullyQualifiedErrorId : System.IndexOutOfRangeException

which seems to come from @(Get-Command cmake.exe) returning an empty array.

从第 71 行的 build.libgit2.ps1 开始，在 cmake.exe 不可用时重现构建过程。检查如何处理 Get-Command cmake.exe 的空结果，然后在没有 CMake 的情况下运行脚本，以验证它报告的是清晰且可操作的错误，而不是 IndexOutOfRangeException。