web: Show panics in console in prql-js

CHANGELOG.md

@@ -12,6 +12,8 @@
 
 **Web**:
 
+- Any panics in the compiler are now printed to the console (@max-sixty, #3446)
+
 **Integrations**:
 
 **Internal changes**:

bindings/prql-js/Cargo.toml

@@ -22,9 +22,15 @@ prql-compiler = {path = "../../crates/prql-compiler", default-features = false}
 wasm-bindgen = "0.2.87"
 
 # The `console_error_panic_hook` crate provides better debugging of panics by
-# logging them with `console.error`. This is great for development, but requires
-# all the `std::fmt` and `std::panicking` infrastructure, so isn't great for
-# code size when deploying.
+# logging them with `console.error`. While the docs state that "This is great
+# for development, but requires all the `std::fmt` and `std::panicking`
+# infrastructure, so isn't great for code size when deploying.", on testing with
+# `--no-default-features`,
+# `prql/target/wasm32-unknown-unknown/release/prql_js.wasm` is 7.416MB vs
+# 7.408MB. Maybe because we're already including lots of that with other library
+# features? Even running `wasm-opt prql_js.wasm` makes similiarly sized files of
+# 5.7M. Feel free to try removing this as part of reducing code size (would be
+# good to have a much smaller code size...). 
 console_error_panic_hook = {version = "0.1.7", optional = true}
 
 [target.'cfg(target_family="wasm")'.dev-dependencies]

bindings/prql-js/src/lib.rs

@@ -1,7 +1,5 @@
 #![cfg(target_family = "wasm")]
 
-mod utils;
-
 use std::str::FromStr;
 
 use prql_compiler::Target;
@@ -117,6 +115,13 @@ impl From<CompileOptions> for prql_compiler::Options {
 }
 
 fn return_or_throw(result: Result<String, prql_compiler::ErrorMessages>) -> Option<String> {
+    // When the `console_error_panic_hook` feature is enabled, we can call the
+    // `set_panic_hook` function at least once during initialization, and then
+    // we will get better error messages if our code ever panics. See
+    // `Cargo.toml` for notes.
+    #[cfg(feature = "console_error_panic_hook")]
+    console_error_panic_hook::set_once();
+
     match result {
         Ok(sql) => Some(sql),
         Err(e) => wasm_bindgen::throw_str(&e.to_json()),