Don't explode if the SdkConfig isn't available

This can happen prior to logging in, for some reason.

Signed-off-by: Travis Ralston <travpc@gmail.com>

src/components/views/elements/SettingsCheckbox.js

@@ -64,7 +64,7 @@ module.exports = React.createClass({
                        value={this.props.value}
                        checked={val === this.props.value}
                        onChange={this.onChange}
-                       />
+                />
             );
         }
 

src/settings/ConfigSettingsHandler.js

@@ -24,7 +24,8 @@ import SdkConfig from "../SdkConfig";
  */
 export default class ConfigSettingsHandler extends SettingsHandler {
     getValue(settingName, roomId) {
-        const settingsConfig = SdkConfig.get()["settingDefaults"];
+        const config = SdkConfig.get() || {};
+        const settingsConfig = config["settingDefaults"];
         if (!settingsConfig || !settingsConfig[settingName]) return null;
         return settingsConfig[settingName];
     }