Perl: propagate errors. When an error happens, the ctx->error bit is now set, and croak() is called to terminate further processing. The ctx->error bit is checked in ngx_http_perl_call_handler() to cancel further processing, and is also checked in various output functions - to make sure these won't be called if croak() was handled by an eval{} in perl code. In particular, this ensures that output chain won't be called after errors, as filters might not expect this to happen. This fixes some segmentation faults under low memory conditions. Also this stops request processing after filter finalization or request body reading errors. For cases where an HTTP error status can be additionally returned (for example, 416 (Requested Range Not Satisfiable) from the range filter), the ctx->status field is also added.