Feature: Better error handling/reporting (#1670)

* utils: re-export "anyhow" unconditionally

even for wasm targets.

* utils/errors: Share wasm-compatible code

and move everything that can't run in wasm into a separate submodule.

* utils: Share "errors" module unconditionally

The module is now structured such that all code incompatible with wasm
targets lives in its own submodule that isn't included when compiling
for wasm targets.

* utils/errors: Add "Help wanted" doc section

that informs the reader about the endeavour to improve error handling
throughout the zellij code base.

* plugins: Handle errors returned by `zellij_tile`

now that the panic calls have been removed.

* utils/errors: Extend `anyhow::Result` with traits

that allow for easy/concise logging of `anyhow::Result` types and
panicking the application when they are fatal or non-fatal.

* utils/errors: Fix doctest

* utils/errors: Add prelude

that applications can import to conveniently access the error handling
functionality part of the module. Re-exports some parts and macros from
anyhow and the `LoggableError` and `FatalError` traits.

* server/screen: Adopt error handling

and make all fallible functions from the public API return a `Result`.
Append error contexts in all functions that can come across error types
to allow tracing where an error originates and what lead there.

* server/lib: Catch errors from `screen`

and make them `fatal`. This will log the errors first, before unwrapping
on the error type and panicking the application.

* server/unit/screen: Fix unit tests

and unwrap on the `Result` types introduced from the new error handling.

* utils/errors: Track error source

in calls to `fatal`, so we keep track of the location where the panic
really originates. Otherwise, any call to `fatal` will show the code in
`errors` as source, which of course isn't true.
Also change the error formatting and do not call `to_log` for fatal
errors anymore, because the panic is already logged and contains much
more information.

* utils/errors: Update `FatalError` docs

* plugins: Undo accidental modifications

* utils/errors: Improve module docs

explain some error handling facilities and the motivation behind using
them.

* server/screen: Remove `Result` from Infallible

functions that are part of the public API.

zellij-server/src/lib.rs

@@ -40,7 +40,7 @@ use zellij_utils::{
     cli::CliArgs,
     consts::{DEFAULT_SCROLL_BUFFER_SIZE, SCROLL_BUFFER_SIZE},
     data::{Event, PluginCapabilities},
-    errors::{ContextType, ErrorInstruction, ServerContext},
+    errors::{ContextType, ErrorInstruction, FatalError, ServerContext},
     input::{
         command::{RunCommand, TerminalAction},
         get_mode_info,
@@ -691,7 +691,8 @@ fn init_session(
                     max_panes,
                     client_attributes_clone,
                     config_options,
-                );
+                )
+                .fatal();
             }
         })
         .unwrap();