commands return integer value if possible, fixes #408

handle infinite values as infinities.

src/main/java/carpet/script/value/NullValue.java

@@ -68,4 +68,9 @@ public class NullValue extends NumericValue // TODO check nonsingleton code
     {
         return JsonNull.INSTANCE;
     }
+
+    @Override
+    public boolean isNull() {
+        return true;
+    }
 }

src/main/java/carpet/script/value/NumericValue.java

@@ -44,11 +44,13 @@ public class NumericValue extends Value
         }
         try
         {
+            if (value.isInfinite()) return "INFINITY";
+            if (value.isNaN()) return "NaN";
             return BigDecimal.valueOf(value).stripTrailingZeros().toPlainString();
         }
         catch (NumberFormatException exc)
         {
-            throw new ArithmeticException("Incorrect number format for "+value);
+            throw new InternalExpressionException("Incorrect number format for "+value);
         }
     }
 
@@ -121,6 +123,7 @@ public class NumericValue extends Value
     }
     public Value divide(Value v)
     {
+        //if (1+2==3) throw new ArithmeticException("Booyah");
         if (v instanceof NumericValue)
         {
             return new NumericValue(getDouble() / ((NumericValue) v).getDouble() );

src/main/java/carpet/script/value/Value.java

@@ -213,4 +213,6 @@ public abstract class Value implements Comparable<Value>, Cloneable
     {
         return new JsonPrimitive(getString());
     }
+
+    public boolean isNull() { return false; }
 }