dotnet sln remove now throws NullReferenceException on bad paths

[AHelper]

Describe the bug

Running dotnet sln remove on an path that isn't in the solution throws a NullReferenceExceptions instead of gracefully printing a message. This only happens when:

• A .slnx file is used instead of a .sln file
• The .slnx has at least one project in it. An empty slnx file will correctly print the message.

Steps to reproduce

mkdir test ; cd test
dotnet new sln -f slnx
dotnet new classlib
dotnet sln . add .
dotnet -d sln . remove invalid

Expected behavior

This should print out:

$ dotnet sln . remove invalid
Project `invalid` could not be found in the solution.

Above is from running in a mcr.microsoft.com/dotnet/sdk:10.0.100-preview.2 container

Actual behavior

It currently prints out:

$ dotnet sln . remove invalid
Object reference not set to an instance of an object.
$ dotnet -d sln . remove invalid
Telemetry is: Enabled
Microsoft.DotNet.Cli.Utils.GracefulException: Object reference not set to an instance of an object.
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.DotNet.Tools.Sln.Remove.RemoveProjectFromSolutionCommand.<>c__DisplayClass4_0.<RemoveProjectsAsync>b__0(SolutionProjectModel p)
   at System.Linq.Enumerable.ArrayWhereIterator`1.GetCount(Boolean onlyIfCheap, ReadOnlySpan`1 source, Func`2 predicate)
   at Microsoft.DotNet.Tools.Sln.Remove.RemoveProjectFromSolutionCommand.RemoveProjectsAsync(String solutionFileFullPath, IEnumerable`1 projectPaths, CancellationToken cancellationToken)
   at Microsoft.DotNet.Tools.Sln.Remove.RemoveProjectFromSolutionCommand.Execute()
   --- End of inner exception stack trace ---
   at Microsoft.DotNet.Tools.Sln.Remove.RemoveProjectFromSolutionCommand.Execute()
   at System.CommandLine.Invocation.InvocationPipeline.Invoke(ParseResult parseResult)
   at System.CommandLine.ParseResult.Invoke()
   at Microsoft.DotNet.Cli.Program.ProcessArgs(String[] args, TimeSpan startupTime, ITelemetry telemetryClient)

The above is from a mcr.microsoft.com/dotnet/sdk:10.0.100-preview.3 container.

Is this a regression?

I tracked the breakage down to SDK 10.0.100-preview.3. SDK 10.0-100-preview.2 is ok. SDK 9.0.315 (latest at time of writing) is also unaffected.

Are there any workarounds?

You'll have to check the paths manually before calling dotnet sln remove. Since when it throws, it stops processing the rest of the arguments.

dotnet --info output

.NET SDK:
 Version:           10.0.301
 Commit:            96856fd726
 Workload version:  10.0.300-manifests.8c7d7c03
 MSBuild version:   18.6.4+96856fd72

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.26200
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\10.0.301\

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
  Version:      10.0.9
  Architecture: x64
  Commit:       901ca94124

.NET SDKs installed:
  6.0.428 [C:\Program Files\dotnet\sdk]
  7.0.410 [C:\Program Files\dotnet\sdk]
  8.0.422 [C:\Program Files\dotnet\sdk]
  9.0.100-rc.2.24474.11 [C:\Program Files\dotnet\sdk]
  9.0.315 [C:\Program Files\dotnet\sdk]
  10.0.109 [C:\Program Files\dotnet\sdk]
  10.0.301 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.28 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.0-rc.2.24474.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 10.0.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.28 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.0-rc.2.24473.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 10.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.28 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.0-rc.2.24474.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 10.0.9 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

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IDE version

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Other details

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