- a yaml parser error can only be fixed by the user uploading a file, therefore it should be a 4xx, not a 5xx error
- an amp parser error indicates the amperize module is unable to handle a genuine case, and needs to be fixed at the code level
fixes 10883
- fixed an issue where /amp/ pages would cause an infinite redirect loop
- this only occurred when amp was disabled, and query params were passed to the /amp/ url
- this fix resolves the issue by not assuming /amp/ is the end of the URL
- it also checks for `/amp/` (both slashes) and replaces one
refs #10790
- Moved /core/apps into core/frontend
- Moved /core/server/helpers to /core/frontend/helpers along with /core/server/services/themes
- Changed helper location in overrides
- Moved /core/server/services/routing to /core/frontend/services
- Moved /core/server/services/url to /core/frontend/services
- Moved /core/server/data/meta to /core/frontend/meta
- Moved /core/server/services/rss to /core/frontend/services
- Moved /core/server/data/xml to /core/frontend/services
