Predefined type 'System.String' is not defined or imported in C#

Context:

I Code C# using Dotnet-cli with Visual Studio Code on a Mac. This worked fine until a few days ago where every time I open Visual Studio Code it gives me millions of errors about "Predefined type 'System.String' is not defined or imported", "Predefined type 'System.Object' is not defined or imported", and many more errors about the System Namespace.

Question:

Why is this happening and how do I fix this?

Things I have tried:

1. Clean project using dotnet (Clean Succeeded)
2. Rebuilding project using dotnet (Build Succeeded)
3. Uninstalling and Reinstalling c# extension

.vscode File:

tasks.json:

{
    // See https://go.microsoft.com/fwlink/?LinkId=733558
    // for the documentation about the tasks.json format
    "version": "2.0.0",
    "tasks": [
        {
            "label": "build",
            "command": "dotnet",
            "type": "shell",
            "args": [
                "build",
                // Ask dotnet build to generate full paths for file names.
                "/property:GenerateFullPaths=true",
                // Do not generate summary otherwise it leads to duplicate errors in Problems panel
                "/consoleloggerparameters:NoSummary"
            ],
            "group": "build",
            "presentation": {
                "reveal": "silent"
            },
            "problemMatcher": "$msCompile"
        }
    ]
}

launch.json:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": ".NET Core Launch (console)",
            "type": "coreclr",
            "request": "launch",
            "WARNING01": "*********************************************************************************",
            "WARNING02": "The C# extension was unable to automatically decode projects in the current",
            "WARNING03": "workspace to create a runnable launch.json file. A template launch.json file has",
            "WARNING04": "been created as a placeholder.",
            "WARNING05": "",
            "WARNING06": "If OmniSharp is currently unable to load your project, you can attempt to resolve",
            "WARNING07": "this by restoring any missing project dependencies (example: run 'dotnet restore')",
            "WARNING08": "and by fixing any reported errors from building the projects in your workspace.",
            "WARNING09": "If this allows OmniSharp to now load your project then --",
            "WARNING10": "  * Delete this file",
            "WARNING11": "  * Open the Visual Studio Code command palette (View->Command Palette)",
            "WARNING12": "  * run the command: '.NET: Generate Assets for Build and Debug'.",
            "WARNING13": "",
            "WARNING14": "If your project requires a more complex launch configuration, you may wish to delete",
            "WARNING15": "this configuration and pick a different template using the 'Add Configuration...'",
            "WARNING16": "button at the bottom of this file.",
            "WARNING17": "*********************************************************************************",
            "preLaunchTask": "build",
            "program": "${workspaceFolder}/bin/Debug/<insert-target-framework-here>/<insert-project-name-here>.dll",
            "args": [],
            "cwd": "${workspaceFolder}",
            "console": "internalConsole",
            "stopAtEntry": false
        },
        {
            "name": ".NET Core Attach",
            "type": "coreclr",
            "request": "attach",
            "processId": "${command:pickProcess}"
        }
    ]
}

Output When Run:

Debug Console Tab:

-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/Users/khaled/Projects/new/bin/Debug/netcoreapp3.1/new.dll'. Symbols loaded.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Runtime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Diagnostics.Process.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.ComponentModel.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Console.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Runtime.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Threading.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Text.Encoding.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Not Enough Args
The program '[82385] new.dll' has exited with code 0 (0x0).

.csproj File:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.1</TargetFramework>
  </PropertyGroup>

</Project>

Problems:

1. In the obj file, Debug/netcoreapp3.1, .NETCoreApp,Version=v3.1.AssemblyAttributes.cs and new.AssemblyInfo.cs
2. The program file
3. .csproj file

Additional Info:

1. Program Runs Successfully