add else blocks and nicer comments for fauna example

src/functions-templates/js/fauna-crud/fauna-crud.js

@@ -4,24 +4,45 @@ exports.handler = async (event, context) => {
 
   switch (event.httpMethod) {
     case 'GET':
+      // e.g. GET /.netlify/functions/fauna-crud
       if (segments.length === 0) {
         return require('./read-all').handler(event, context)
       }
+      // e.g. GET /.netlify/functions/fauna-crud/123456
       if (segments.length === 1) {
         event.id = segments[0]
         return require('./read').handler(event, context)
+      } else {
+        return {
+          statusCode: 500,
+          body:
+            'too many segments in GET request, must be either /.netlify/functions/fauna-crud or /.netlify/functions/fauna-crud/123456'
+        }
       }
     case 'POST':
+      // e.g. POST /.netlify/functions/fauna-crud with a body of key value pair objects, NOT strings
       return require('./create').handler(event, context)
     case 'PUT':
+      // e.g. PUT /.netlify/functions/fauna-crud/123456 with a body of key value pair objects, NOT strings
       if (segments.length === 1) {
         event.id = segments[0]
         return require('./update').handler(event, context)
+      } else {
+        return {
+          statusCode: 500,
+          body: 'invalid segments in POST request, must be /.netlify/functions/fauna-crud/123456'
+        }
       }
     case 'DELETE':
+      // e.g. DELETE /.netlify/functions/fauna-crud/123456
       if (segments.length === 1) {
         event.id = segments[0]
         return require('./delete').handler(event, context)
+      } else {
+        return {
+          statusCode: 500,
+          body: 'invalid segments in DELETE request, must be /.netlify/functions/fauna-crud/123456'
+        }
       }
   }
   return { statusCode: 500, body: 'unrecognized HTTP Method, must be one of GET/POST/PUT/DELETE' }