Fix void auto-return bug with empty stmts

src/compiler/NubLang/Generation/QBE/QBEGenerator.cs

@@ -363,7 +363,7 @@ public class QBEGenerator
         EmitBlock(funcDef.Body);
 
         // Implicit return for void functions if no explicit return has been set
-        if (funcDef.Signature.ReturnType is VoidTypeNode && funcDef.Body.Statements is [.., not ReturnNode])
+        if (funcDef.Signature.ReturnType is VoidTypeNode && funcDef.Body.Statements.LastOrDefault() is not ReturnNode)
         {
             _writer.Indented("ret");
         }
@@ -400,7 +400,7 @@ public class QBEGenerator
             EmitBlock(function.Body);
 
             // Implicit return for void functions if no explicit return has been set
-            if (function.Signature.ReturnType is VoidTypeNode && function.Body.Statements is [.., not ReturnNode])
+            if (function.Signature.ReturnType is VoidTypeNode && function.Body.Statements.LastOrDefault() is not ReturnNode)
             {
                 _writer.Indented("ret");
             }

src/compiler/NubLang/HexString.cs

@@ -1,38 +0,0 @@
-namespace NubLang;
-
-public static class HexString
-{
-    private static readonly HashSet<string> _used = [];
-
-    private static readonly char[] StringChars = "0123456789abcdef".ToArray();
-
-    public static string CreateUnique(int length)
-    {
-        string hex;
-
-        while (true)
-        {
-            hex = Create(length);
-            if (_used.Add(hex))
-            {
-                break;
-            }
-        }
-
-        return hex;
-    }
-
-    public static string Create(int length)
-    {
-        var rand = new Random();
-        var hexString = "";
-
-        for (var i = 0; i < length; i++)
-        {
-            var randIndex = rand.Next(0, StringChars.Length);
-            hexString += StringChars[randIndex];
-        }
-
-        return hexString;
-    }
-}