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.

1 files changed, 5 insertions, 4 deletions

diff --git a/zellij-utils/src/lib.rs b/zellij-utils/src/lib.rs
index 3cff1f04..e871aeee 100644
--- a/zellij-utils/src/lib.rs
+++ b/zellij-utils/src/lib.rs
@@ -2,6 +2,7 @@ pub mod cli;
 pub mod consts;
 pub mod data;
 pub mod envs;
+pub mod errors;
 pub mod input;
 pub mod pane_size;
 pub mod position;
@@ -12,14 +13,14 @@ pub mod shared;
 #[cfg(not(target_family = "wasm"))]
 pub mod channels; // Requires async_std
 #[cfg(not(target_family = "wasm"))]
-pub mod errors; // Requires async_std (via channels)
-#[cfg(not(target_family = "wasm"))]
 pub mod ipc; // Requires interprocess
 #[cfg(not(target_family = "wasm"))]
 pub mod logging; // Requires log4rs
 
 #[cfg(not(target_family = "wasm"))]
 pub use ::{
-    anyhow, async_std, clap, interprocess, lazy_static, libc, nix, regex, serde, serde_yaml,
-    signal_hook, tempfile, termwiz, vte,
+    async_std, clap, interprocess, lazy_static, libc, nix, regex, serde, serde_yaml, signal_hook,
+    tempfile, termwiz, vte,
 };
+
+pub use anyhow;