Convert NodeInfo.Nothing from a lazy val to an object

daffodil-core/src/main/scala/org/apache/daffodil/runtime1/dpath/NodeInfo.scala

@@ -297,29 +297,32 @@ object NodeInfo extends Enum {
   /**
    * Nothing is the bottom of the type lattice.
    *
-   * It is the return type of the dfdlx:error() function. It's a subtype of
+   * It is the return type of the fn:error() function. It's a subtype of
    * every type (except some special singletons like ArrayType).
    */
-  lazy val Nothing = new TypeNode(
-    Seq(
-      Boolean,
-      Complex,
-      Array,
-      ArrayIndex,
-      Double,
-      Float,
-      Date,
-      Time,
-      DateTime,
-      UnsignedByte,
-      Byte,
-      HexBinary,
-      AnyURI,
-      String,
-      NonEmptyString
-    ),
-    Nil
-  ) with Boolean.Kind
+  protected sealed trait NothingKind extends NodeInfo.Kind
+  case object Nothing
+    extends TypeNode(
+      Seq(
+        Boolean,
+        Complex,
+        Array,
+        ArrayIndex,
+        Double,
+        Float,
+        Date,
+        Time,
+        DateTime,
+        UnsignedByte,
+        Byte,
+        HexBinary,
+        AnyURI,
+        String,
+        NonEmptyString
+      ),
+      Nil
+    )
+    with Boolean.Kind
     with Complex.Kind
     with Array.Kind
     with ArrayIndex.Kind
@@ -332,7 +335,9 @@ object NodeInfo extends Enum {
     with Byte.Kind
     with HexBinary.Kind
     with NonEmptyString.Kind
-    with AnyURI.Kind
+    with AnyURI.Kind {
+    sealed trait Kind extends NothingKind
+  }
 
   /**
    * All complex types are represented by this one type object.

daffodil-test/src/test/resources/org/apache/daffodil/section17/calc_value_properties/outputValueCalc.tdml

@@ -315,6 +315,15 @@
 			</xs:complexType>
 		</xs:element>
 
+		<xs:element name="err_05">
+			<xs:complexType>
+				<xs:sequence>
+					<xs:element name="err1" type="xs:string"
+						dfdl:outputValueCalc="{fn:round-half-to-even(fn:error('This is the error string'))}" />
+				</xs:sequence>
+			</xs:complexType>
+		</xs:element>
+
         <xs:element name="refSimpleElementWithOvc">
           <xs:complexType>
             <xs:sequence>
@@ -766,6 +775,26 @@
 
 	</tdml:unparserTestCase>
 
+	<tdml:unparserTestCase name="errorInRoundHalfToEven"
+	    root="err_05" model="outputValueCalc-Embedded.dfdl.xsd"
+	    description="Calling fn:error() inside fn:round-half-to-even()">
+		<tdml:infoset>
+			<tdml:dfdlInfoset xmlns:xs="http://www.w3.org/2001/XMLSchema"
+				xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+				<ex:err_05>
+					<err1>a</err1>
+				</ex:err_05>
+			</tdml:dfdlInfoset>
+		</tdml:infoset>
+		<tdml:document />
+
+	    <tdml:errors>
+		    <tdml:error>Unparse Error</tdml:error>
+		    <tdml:error>This is the error string</tdml:error>
+	    </tdml:errors>
+
+	</tdml:unparserTestCase>
+
     <tdml:unparserTestCase name="refSimpleTypeElemWithOvc"
       root="refSimpleElementWithOvc" model="outputValueCalc-Embedded.dfdl.xsd"
       description="An element referencing a simpleType Elem with an OVC" roundTrip="false">

daffodil-test/src/test/scala/org/apache/daffodil/section17/calc_value_properties/TestOutputValueCalc.scala

@@ -58,6 +58,7 @@ class TestOutputValueCalc1 extends TdmlTests {
   @Test def errorOneArg = test
   @Test def errorTwoArg = test
   @Test def errorThreeArg = test
+  @Test def errorInRoundHalfToEven = test
 
   // DAFFODIL-1701
   @Test def refSimpleTypeElemWithOvc = test