Fix a few IDE warnings (#1345)

src/main/java/carpet/script/language/Operators.java

@@ -22,7 +22,7 @@ import java.util.List;
 import java.util.Map;
 
 public class Operators {
-    public static final Map<String, Integer> precedence = new HashMap<String,Integer>() {{
+    public static final Map<String, Integer> precedence = new HashMap<String, Integer>() {{
         put("attribute~:", 80);
         put("unary+-!...", 60);
         put("exponent^", 40);

src/main/java/carpet/script/language/Sys.java

@@ -11,7 +11,6 @@ import carpet.script.value.BooleanValue;
 import carpet.script.value.FunctionValue;
 import carpet.script.value.ListValue;
 import carpet.script.value.MapValue;
-import carpet.script.value.NullValue;
 import carpet.script.value.NumericValue;
 import carpet.script.value.StringValue;
 import carpet.script.value.Value;