Gracefully handle invalid dateTime param values

lib/soap.js

@@ -210,7 +210,10 @@ function SetParameterValues(xml, methodRequest) {
   for (const p of methodRequest.parameterList) {
     const pvs = paramList.node("ParameterValueStruct");
     pvs.node("Name").text(p[0]);
-    pvs.node("Value").attr({"xsi:type": p[2]}).text(p[1]);
+    if (p[2] === 'xsd:dateTime' && Number.isInteger(p[1]))
+      pvs.node("Value").attr({"xsi:type": p[2]}).text((new Date(p[1])).toISOString());
+    else
+      pvs.node("Value").attr({"xsi:type": p[2]}).text(p[1]);
   }
 
   el.node("ParameterKey").text(methodRequest.parameterKey || "");