[bugfix] Fix comparison of NaN values for xs:float and xs:double

Author: adamretter

exist-core/src/main/java/org/exist/xquery/value/DoubleValue.java

@@ -147,7 +147,11 @@ public boolean isPositive() {
     @Override
     protected @Nullable IntSupplier createComparisonWith(final NumericValue other) {
         final IntSupplier comparison;
-        if (isInfinite() && other.isInfinite() && isPositive() == other.isPositive()) {
+        if (isNaN()) {
+            comparison = () -> Constants.INFERIOR;
+        } else if (other.isNaN()) {
+            comparison = () -> Constants.SUPERIOR;
+        } else if (isInfinite() && other.isInfinite() && isPositive() == other.isPositive()) {
             comparison = () -> Constants.EQUAL;
         } else if (other instanceof IntegerValue) {
             comparison = () -> BigDecimal.valueOf(value).compareTo(new BigDecimal(((IntegerValue) other).value));

exist-core/src/main/java/org/exist/xquery/value/FloatValue.java

@@ -150,8 +150,11 @@ public boolean isPositive() {
     @Override
     protected @Nullable IntSupplier createComparisonWith(final NumericValue other) {
         final IntSupplier comparison;
-
-        if (isInfinite() && other.isInfinite() && isPositive() == other.isPositive()) {
+        if (isNaN()) {
+            comparison = () -> Constants.INFERIOR;
+        } else if (other.isNaN()) {
+            comparison = () -> Constants.SUPERIOR;
+        } else if (isInfinite() && other.isInfinite() && isPositive() == other.isPositive()) {
             comparison = () -> Constants.EQUAL;
         } else if (other instanceof IntegerValue) {
             comparison = () -> BigDecimal.valueOf(value).compareTo(new BigDecimal(((IntegerValue)other).value));