During a read-only passage of Wikipedia today (T194939, https://gerrit.wikimedia.org/r/#/c/435755/), I wanted to try to save a page via the mobile site.
After opening the editor, makes a small change in the code, clicking the Save button displays no messages, no errors. Interface just tries to save the page, but it can't. After a few seconds, the button becomes clickable again. The user can click several times on the button infinitely, the site tries again.
It would simply appear that the software does not take this case into account.
This is quite problematic since the mediawiki desktop website displays an error message chosen by the administrator. Mobile users do not see this information. Nothing indicates that it is temporarily normal that the site is not visible.
**Analysis (@Jdrewniak) **
From my analysis, I think there are 4 distinct bugs here:
1. Prior to editing, there is no indication the site is in read-only mode.
2. In **mobile VE**, saving fails with a "<apierror-readonly>" message (correctly), but the actual message text does not show up. (note: this could be a local error, should verify on another machine).
3. In **mobile source editor** after the save fails, a toast is presented with a generic error message, but the toast is not visible until you scroll down, and the toast appears "underneath" the article content. The error message should probably display the "apierror-readonly" message [EditorOverlay.js#L285](https://github.com/wikimedia/mediawiki-extensions-MobileFrontend/blob/f4c03a10ce202eb70b7b4efd1fe62f58d2c057b0/resources/mobile.editor.overlay/EditorOverlay.js#L285)
4. In the **EditorGateway** the failed save falls through as a generic "http" error. The actual nature of the error is not considered when presenting the error message. [EditorGateway.js#L233](https://github.com/wikimedia/mediawiki-extensions-MobileFrontend/blob/e56b98c7912241561be91f5eb8c85935f8829974/resources/mobile.editor.api/EditorGateway.js#L233)