Some fixes in tuistenv

Package.resolved

@@ -19,15 +19,6 @@
           "version": null
         }
       },
-      {
-        "package": "SwiftShell",
-        "repositoryURL": "git@github.com:tuist/SwiftShell.git",
-        "state": {
-          "branch": null,
-          "revision": "f9d6e23a382cf7ccf728d7e046b1b91157ffeb56",
-          "version": null
-        }
-      },
       {
         "package": "xcodeproj",
         "repositoryURL": "git@github.com:tuist/xcodeproj.git",

Sources/TuistCore/Utils/System.swift

@@ -8,17 +8,22 @@ public protocol Systeming {
     func popen(_ args: [String], verbose: Bool) throws
 }
 
-struct SystemError: FatalError {
+public struct SystemError: FatalError {
     let stderror: String?
     let exitcode: Int32
 
-    var type: ErrorType {
+    public var type: ErrorType {
         return .abort
     }
 
-    var description: String {
+    public var description: String {
         return stderror ?? "Error running command"
     }
+    
+    public init(stderror: String? = nil, exitcode: Int32) {
+        self.stderror = stderror
+        self.exitcode = exitcode
+    }
 }
 
 public struct SystemResult {

Sources/TuistCoreTesting/Utils/MockSystem.swift

@@ -1,5 +1,5 @@
 import Foundation
-@testable import TuistCore
+import TuistCore
 
 public final class MockSystem: Systeming {
     private var stubs: [String: (stderror: String?, stdout: String?, exitstatus: Int32?)] = [:]

Sources/TuistEnvKit/Installer/Installer.swift

@@ -56,15 +56,11 @@ final class Installer: Installing {
             if printing { printer.print("Checking out \(version) reference") }
             try system.capture("git", "-C", temporaryDirectory.path.asString, "checkout", version, verbose: verbose).throwIfError()
             if printing { printer.print("Building using Swift (it might take a while)") }
-            let os = ProcessInfo.processInfo.operatingSystemVersion
-            let target = "x86_64-apple-macosx\(os.majorVersion).\(os.minorVersion)"
             let swiftPath = try system.capture("/usr/bin/xcrun", "-f", "swift", verbose: false).stdout.chuzzle()!
             try system.capture(swiftPath, "build",
                                "--package-path", temporaryDirectory.path.asString,
                                "--configuration", "release",
                                "-Xswiftc", "-static-stdlib",
-                               "-Xswiftc", "-target",
-                               "-Xswiftc", target,
                                verbose: verbose).throwIfError()
 
             // Copying built files