1b78ca8c5e
If texture allocation fails (e.g. on an old GPU with size limit 2048) then `update_fbo` would return `FALSE` but leaves `priv->offscreen` as non-NULL. So the next paint will try to use the offscreen with a `NULL` texture and crashes. The solution is simply to ensure that `priv->offscreen` is NULL if there is no `priv->texture`, so the default (non-offscreen) paint path gets used instead. Bug reported and fix provided by Gert van de Kraats. https://launchpad.net/bugs/1795774 (cherry picked from commit f31cf0c3ef99b27c0b2c0161fc9fc1eb82778b2e)