Fix

Author: Ives van Hoorne

src/app/pages/Sandbox/index.js

@@ -131,7 +131,8 @@ class SandboxPage extends React.PureComponent<Props, $FlowFixMeState> {
       <Container>
         <ThemeProvider
           theme={{
-            templateColor: getTemplateDefinition(sandbox.template).color,
+            templateColor: getTemplateDefinition(sandbox && sandbox.template)
+              .color,
           }}
         >
           <Editor match={match} sandbox={sandbox} />

src/common/templates/index.js

@@ -11,6 +11,10 @@ export const vue = {
 };
 
 export default function getDefinition(theme: 'create-react-app' | 'vue-cli') {
+  if (!theme) {
+    return react;
+  }
+
   if (theme === react.name) {
     return react;
   } else if (theme === vue.name) {