fix: add error handling for attempts to access pages with content-typ…

…e other than json (TYPO3-Headless#319)

lib/lib/context.js

@@ -108,6 +108,15 @@ async function contextMiddleware (context) {
       const response = await app.$typo3.api.getPage(path)
       const { data } = response
 
+      if (path.startsWith('/typo3')) {
+        return setErrorContext(context, { response: { status: 403, message: 'The /typo3 subpage is restricted and unavailable for use.' } })
+      }
+
+      const contentType = response.headers['content-type']
+      if (contentType && !contentType.includes('application/json')) {
+        return setErrorContext(context, { response: { status: 415, message: 'Unsupported content-type: \'application/json\' expected.' } })
+      }
+
       if (context.res) {
         setResponseHeaders(context, response.headers)
       }