Roslyn crashes when reporting an error with an "unusual" compilation unit name

**Version Used**: .NET 9.0.100

**Steps to Reproduce**:

1. Create a new console application (`dotnet new console`)
2. Edit Program.cs to:

```csharp
#line 100 ":invalid:"
int x = 5.0;
```

3. Run `dotnet build`

**Expected Behavior**:

Normal error messages without a crash.

**Actual Behavior**:

```text
C:\Program Files\dotnet\sdk\9.0.100\Roslyn\Microsoft.CSharp.Core.targets(89,5): error MSB6006: "csc.dll" exited with code 1.
```

**Notes**:

- Visual Studio indicates csc.dll exiting with code 1 as well
- This is not reproducible in SharpLab - I suspect it's injecting its own `#line` directives
- Changing `":invalid:"` to `"valid"` produces normal error messages.
- Names of `"."`, `".."` and `"..."` produce some interesting results
- Changing the code to only produce a warning (e.g. just `int x = 5;` which results in CS0219) when using `":invalid:"` is weird - the build succeeds without issuing a warning at all