refactor(tvix/eval): factor CatchableErrorKind out of ErrorKind r/6649

This commit creates a separate enum for "catchable" errors (the kind
that `builtins.tryEval` can detect).

Change-Id: Ie81d1112526d852255d9842f67045f88eab192af
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9287
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index d701fa08a0..322f917108 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -17,7 +17,7 @@ use crate::vm::generators::{self, GenCo};
 use crate::warnings::WarningKind;
 use crate::{
     self as tvix_eval,
-    errors::ErrorKind,
+    errors::{CatchableErrorKind, ErrorKind},
     value::{CoercionKind, NixAttrs, NixList, NixString, SharedThunkSet, Thunk, Value},
 };
 
@@ -893,7 +893,9 @@ mod pure_builtins {
 
     #[builtin("throw")]
     async fn builtin_throw(co: GenCo, message: Value) -> Result<Value, ErrorKind> {
-        Err(ErrorKind::Throw(message.to_str()?.to_string()))
+        Err(ErrorKind::CatchableErrorKind(CatchableErrorKind::Throw(
+            message.to_str()?.to_string(),
+        )))
     }
 
     #[builtin("toString")]