foo.patch

diff --git a/frontend/src/app/containers/App/index.js b/frontend/src/app/containers/App/index.js
index 5d34ca2d..b2b3197a 100644
--- a/frontend/src/app/containers/App/index.js
+++ b/frontend/src/app/containers/App/index.js
@@ -1,7 +1,7 @@
 /* global ga */
 import { MessageContext } from "fluent/compat";
 import { negotiateLanguages } from "fluent-langneg/compat";
-import { LocalizationProvider } from "fluent-react/compat";
+import { LocalizationProvider, isReactLocalization } from "fluent-react/compat";
 import React, { Component } from "react";
 import { connect } from "react-redux";
 
@@ -45,6 +45,11 @@ export function shouldShowUpgradeWarning(hasAddon, hasAddonManager, thisIsFirefo
   return true;
 }
 
+let xxx = false;
+function logL10n(id) {
+  if (xxx) { console.error(`missing l10n for ${id}`); }
+}
+
 
 class App extends Component {
   constructor(props) {
@@ -145,6 +150,7 @@ class App extends Component {
     );
 
     Promise.all(promises).then(() => {
+      xxx = true;
       this.props.setLocalizations(langs);
       const staticNode = document.getElementById("static-root");
       if (staticNode) {
@@ -177,12 +183,30 @@ class App extends Component {
         }
       }
     }
+    const Logger = ({children}, context) => {
+      if (!context.l10n._getMessageContext) {
+        context.l10n._getMessageContext = context.l10n.getMessageContext
+        context.l10n.getMessageContext = (function (id) {
+          const ctx = this._getMessageContext(id)
+          if (!ctx) {
+            logL10n(id);
+          }
+          return ctx;
+        }).bind(context.l10n)
+      }
+      return children
+    }
+    Logger.contextTypes = {
+      l10n: isReactLocalization
+    }
 
     return <LocalizationProvider messages={ generateMessages(
       this.props.negotiatedLanguages,
       this.props.localizations
     ) }>
-      { React.cloneElement(this.props.children, this.props) }
+      <Logger>
+        { React.cloneElement(this.props.children, this.props) }
+      </Logger>
     </LocalizationProvider>;
   }
 }