Don't verify file is executable before running it.

Also remove unneeded Equatable implementation.

Sources/SwiftShell/Command.swift

@@ -83,7 +83,7 @@ extension CommandRunning {
 // MARK: CommandError
 
 /** Error type for commands. */
-public enum CommandError: Error {
+public enum CommandError: Error, Equatable {
 
 	/** Exit code was not zero. */
 	case returnedErrorCode(command: String, errorcode: Int)
@@ -113,19 +113,6 @@ extension CommandError: CustomStringConvertible {
 	}
 }
 
-extension CommandError: Equatable {
-	static public func == (e1: CommandError, e2: CommandError) -> Bool {
-		switch (e1, e2) {
-		case (.returnedErrorCode(let c1), .returnedErrorCode(let c2)):
-			return c1.errorcode == c2.errorcode && c1.command == c2.command
-		case (.inAccessibleExecutable(let c1), .inAccessibleExecutable(let c2)):
-			return c1 == c2
-		case (.inAccessibleExecutable, .returnedErrorCode), (.returnedErrorCode, .inAccessibleExecutable):
-			return false
-		}
-	}
-}
-
 // MARK: run
 
 /// Output from a `run` command.

Sources/SwiftShell/Process.swift

@@ -16,10 +16,11 @@ extension Process {
 	///
 	/// - throws: CommandError.inAccessibleExecutable if command could not be executed.
 	public func launchThrowably() throws {
-		guard Files.isExecutableFile(atPath: self.executableURL!.path) else {
+		do {
+			try run()
+		} catch CocoaError.fileNoSuchFile {
 			throw CommandError.inAccessibleExecutable(path: self.executableURL!.lastPathComponent)
 		}
-		try run()
 	}
 
 	/// Waits until process is finished.