Trouble submitting errors using Airbrake.notify({})

I'm calling:

  Airbrake.notify
    params:
      message: "Error saving record"
      json: JSON.stringify(model)
    message: 'Save Error in Christo'

which is sending the following data across the wire:

<?xml version="1.0" encoding="UTF-8"?><notice version="2.0"><api-key>bd88b60a2fd63f921372b7daa3b24b49</api-key><notifier><name>airbrake_js</name><version>0.1.0</version><url>http://airbrake.io</url></notifier><error><class>Error</class><message>Save Error in Christo</message><backtrace><line method="{anonymous}([object Object],[object Object])" file="[PROJECT_ROOT]/assets/discover_main.js" number="8160" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/discover_main.js" number="8369" /><line method="{anonymous}([object Object],(function (n, o, p) {i(n, o);return m._store(o);}),(function () {return e(h, l);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8403" /><line method="{anonymous}([object Object],&#34;error&#34;,&#34;&#34;)" file="[PROJECT_ROOT]/assets/discover_main.js" number="8369" /><line method="{anonymous}([object Object],[object Array])" file="[PROJECT_ROOT]/assets/common.js" number="324" /><line method="w(422,&#34;error&#34;,[object Object],&#34;Connection: close\nDate: Thu, 02 Feb 2012 04:57:52 GMT\nContent-Type: application/xml; charset=utf-8\nX-Runtime: 332\nContent-Length: 2054\nCache-Control: no-cache\n&#34;)" file="[PROJECT_ROOT]/assets/common.js" number="1431" /><line method="{anonymous}()" file="[PROJECT_ROOT]/assets/common.js" number="1514" /><line method="{anonymous}([object Object],w)" file="[PROJECT_ROOT]/assets/common.js" number="1515" /><line method="{anonymous}((void 0))" file="[PROJECT_ROOT]/assets/common.js" number="1466" /><line method="{anonymous}(&#34;update&#34;,[object Object],[object Object])" file="[PROJECT_ROOT]/assets/discover_main.js" number="8379" /><line method="{anonymous}([object Object],(function (n, o, p) {i(n, o);return m._store(o);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8373" /><line method="{anonymous}([object Object],0,[object Array])" file="[PROJECT_ROOT]/assets/discover_main.js" number="8358" /><line method="{anonymous}([object Array],(function (m) {return j.send(m, g, e);}))" file="[PROJECT_ROOT]/assets/common.js" number="1684" /><line method="{anonymous}((function (m) {return j.send(m, g, e);}))" file="[PROJECT_ROOT]/assets/common.js" number="2303" /><line method="{anonymous}([object Object],(function (l, n, j) {var m;return (m = i.shift()) != null ? m.saveMultiple(g, h, l, n, j) : void 0;}),(function (n, o, p) {i(n, o);return m._store(o);}),(function () {return console.log(&#34;finished saving all pois&#34;);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8358" /><line method="{anonymous}((function (n, o, p) {i(n, o);return m._store(o);}),(function () {return console.log(&#34;finished saving all pois&#34;);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8167" /><line method="{anonymous}([object Object],(function (l, n, j) {var m;return (m = i.shift()) != null ? m.saveMultiple(g, h, l, n, j) : void 0;}),(function (n, o, p) {i(n, o, p);return m.findOrStore(n);}),(function () {return console.log(&#34;finished saving all pois&#34;);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8437" /><line method="{anonymous}((function (n, o, p) {i(n, o, p);return m.findOrStore(n);}),(function () {return console.log(&#34;finished saving all pois&#34;);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8167" /><line method="{anonymous}([object Object],(function (l, n, j) {var m;return (m = i.shift()) != null ? m.saveMultiple(g, h, l, n, j) : void 0;}),(function (j, l) {return j.trigger(&#34;save:success&#34;, l);}),(function () {return console.log(&#34;finished saving all pois&#34;);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8514" /><line method="{anonymous}((function (j, l) {return j.trigger(&#34;save:success&#34;, l);}),(function () {return console.log(&#34;finished saving all pois&#34;);}),(function (l, j) {console.log({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});Airbrake.notify({params: {message: &#34;Error saving record&#34;, json: JSON.stringify(l)}, message: &#34;Save Error in Christo&#34;});l.trigger(&#34;save:error&#34;, j);return c.apply(null, arguments);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8167" /><line method="{anonymous}([object Object],(function () {return console.log(&#34;finished saving all pois&#34;);}),(function () {return console.log(&#34;error saving all pois&#34;);}))" file="[PROJECT_ROOT]/assets/discover_main.js" number="8169" /><line method="{anonymous}()" file="[PROJECT_ROOT]/assets/discover_main.js" number="8925" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/discover_main.js" number="13500" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/discover_main.js" number="13314" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/common.js" number="646" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/common.js" number="588" /><line method="{anonymous}([object Object],[object Array],[object HTMLDocument])" file="[PROJECT_ROOT]/assets/common.js" number="633" /><line method="{anonymous}(0,[object HTMLDocument])" file="[PROJECT_ROOT]/assets/common.js" number="739" /><line method="{anonymous}([object Object],(function () {f.event.trigger(a, b, this);}),(void 0))" file="[PROJECT_ROOT]/assets/common.js" number="252" /><line method="{anonymous}((function () {f.event.trigger(a, b, this);}))" file="[PROJECT_ROOT]/assets/common.js" number="189" /><line method="{anonymous}(&#34;save_and_send_content&#34;,(void 0))" file="[PROJECT_ROOT]/assets/common.js" number="739" /><line method="{anonymous}(&#34;save_and_send_content&#34;)" file="[PROJECT_ROOT]/assets/discover_main.js" number="5866" /><line method="{anonymous}()" file="[PROJECT_ROOT]/assets/discover_main.js" number="6513" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/discover_main.js" number="6382" /><line method="M([object Object])" file="[PROJECT_ROOT]/assets/common.js" number="139" /><line method="{anonymous}([object Object])" file="[PROJECT_ROOT]/assets/common.js" number="646" /><line method="{anonymous}([object MouseEvent])" file="[PROJECT_ROOT]/assets/common.js" number="588" /></backtrace></error><request><url>http://0.0.0.0:3000/discover/Cales de Mallorca &#38; Around/1318588#edit</url><component>discover</component><action>index</action><cgi-data><var key="HTTP_USER_AGENT">Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:9.0.1) Gecko/20100101 Firefox/9.0.1</var></cgi-data><params><var key="message">Error saving record</var><var key="json">{&#34;poi&#34;:{&#34;@about&#34;:&#34;/pois/1164781/lang/en&#34;,&#34;id&#34;:&#34;1164781&#34;,&#34;ethyl_id&#34;:null,&#34;feature_id&#34;:null,&#34;place&#34;:{&#34;@about&#34;:&#34;/places/1318588&#34;,&#34;@about_children&#34;:&#34;/places/1318588/children&#34;,&#34;@about_pois&#34;:&#34;/places/1318588/pois&#34;,&#34;id&#34;:1318588,&#34;name&#34;:&#34;Cales de Mallorca &#38; Around&#34;,&#34;ethyl_id&#34;:null,&#34;full_name&#34;:&#34;Europe -&#62; Spain -&#62; Mallorca, Menorca &#38; Ibiza -&#62; Mallorca -&#62; Eastern Mallorca -&#62; Cala Millor to Portocolom -&#62; Cales de Mallorca &#38; Around&#34;},&#34;type&#34;:&#34;Sleep&#34;,&#34;latitude&#34;:null,&#34;longitude&#34;:null,&#34;published&#34;:true,&#34;name&#34;:&#34;S&#39;Aigo&#34;,&#34;searchable_name&#34;:&#34;s&#39;aigo&#34;,&#34;alt_name&#34;:&#34;&#34;,&#34;subtype&#34;:&#34;Rural Hotel&#34;,&#34;telephones&#34;:[{&#34;area_code&#34;:null,&#34;number&#34;:&#34;971 833 050&#34;,&#34;text&#34;:null}],&#34;emails&#34;:[],&#34;urls&#34;:[&#34;www.fincasaigo.com&#34;],&#34;properties&#34;:[{&#34;key&#34;:&#34;attributes&#34;,&#34;value&#34;:&#34;nonsmoking&#34;},{&#34;key&#34;:&#34;attributes&#34;,&#34;value&#34;:&#34;parking&#34;},{&#34;key&#34;:&#34;attributes&#34;,&#34;value&#34;:&#34;swimmingpool&#34;},{&#34;key&#34;:&#34;authorStatus&#34;,&#34;value&#34;:&#34;EditorReady&#34;},{&#34;key&#34;:&#34;cuisine&#34;,&#34;value&#34;:null},{&#34;key&#34;:&#34;prototype&#34;,&#34;value&#34;:null}],&#34;review&#34;:{&#34;summary&#34;:&#34;&#60;p&#62;Just 3km from Cala &#60;em&#62;&#60;strong&#62;Murada&#60;/strong&#62;&#60;/em&#62; sits serene S&#39;Aigo, an ivy-smothered rural estate whose two self-catering stone houses sleep 12 people each. Ideal for groups and families, the rustic stone houses are set amid the shady Mallorcan countryside. Most of the houses have barbecues outside, and some even have a piano.&#60;/p&#62;&#34;,&#34;detail&#34;:&#34;&#34;},&#34;hours&#34;:&#34;&#34;,&#34;price_string&#34;:&#34;r €210-395&#34;,&#34;price_range&#34;:null,&#34;address&#34;:{&#34;street&#34;:&#34;Carretera Portocolom-Portocristo Km2.4&#34;,&#34;locality&#34;:&#34;S&#39;Espinagar&#34;,&#34;postcode&#34;:&#34;07689&#34;,&#34;extras&#34;:null,&#34;region&#34;:&#34;Eastern Mallorca&#34;,&#34;neighbourhood&#34;:null},&#34;transports&#34;:[],&#34;verified_on&#34;:&#34;2011-05-11&#34;,&#34;notes&#34;:&#34;&#34;}}</var></params></request><server-environment><project-root>http://0.0.0.0:3000</project-root><environment-name>local_development</environment-name></server-environment></notice>

but in response I get

<html><body><h1>400 Bad request</h1>
Your browser sent an invalid request.
</body></html>

when I was expecting a new error to be created.

The XML I am sending is valid according to http://airbrake.io/airbrake_2_2.xsd

What am I missing?