Hi,
Welcome to our community! 
Please follow the instruction on this website and make sure all required extensions are installed: https://code.visualstudio.com/docs/other/unity
The .NET SDK contains C#, the programming language. It might be that VS Code has not installed the C# Dev Kit.
Alternatively, you could download and the .NET Framework 4.7.2 (Developer Pack) from the official Microsoft website. Here is the link: https://dotnet.microsoft.com/download/dotnet-framework/net472
I encounter ab error about needing an object reference.
Since there is basically an indefinite number of potential errors, it would be great if you could share a screenshot of your console like you did before. Now I can only guess that you have got a NullReferenceException error.
NullReferenceException means that a reference (“link”) to an instance is missing. Double click on the error message to see to which line in your code it is referring. If you exposed a field in the Inspector, make sure that it’s not empty. Debug.Log might also help you identify variables whose value are null at runtime.
See also:
- Forum User Guides : How to apply code formatting within your post
- Forum User Guides : How to mark a topic as solved