fix(jspromise): convert panics to EngineError::Panic using js_expect (boa-dev#4875)

Part of boa-dev#3241

Converts all 23 panics in jspromise.rs to EngineError::Panic using
js_expect introduced in boa-dev#4828.

Patterns converted:
- `.js_expect()` on internal promise operations that cannot fail
- `.js_expect().map_err(Into::into)` for methods returning
`JsResult<JsPromise>`

Signature changes:
- `resolve()`, `reject()`, `from_result()` → `JsResult<Self>`
- `then()`, `catch()`, `finally()` → `JsResult<JsPromise>`
- `all()`, `all_settled()`, `any()`, `race()` → `JsResult<JsPromise>`
- `into_js_future()` → `JsResult<JsFuture>`

Files modified: 6

Author: KaustubhOG

core/engine/src/builtins/array/from_async.rs

@@ -116,7 +116,7 @@ impl Array {
                     from_array_like(Ok(JsValue::undefined()), &coroutine_state, context)?
                 {
                     // Coroutine yielded. We need to allocate it for a future execution.
-                    JsPromise::resolve(value, context).await_native(
+                    JsPromise::resolve(value, context)?.await_native(
                         NativeCoroutine::from_copy_closure_with_captures(
                             from_array_like,
                             coroutine_state,
@@ -161,7 +161,7 @@ impl Array {
             if let CoroutineState::Yielded(value) =
                 from_async_iterator(Ok(JsValue::undefined()), &coroutine_state, context)?
             {
-                JsPromise::resolve(value, context).await_native(
+                JsPromise::resolve(value, context)?.await_native(
                     NativeCoroutine::from_copy_closure_with_captures(
                         from_async_iterator,
                         coroutine_state,
@@ -449,7 +449,7 @@ fn from_async_iterator(
 
         // i. Assert: result is a throw completion.
         Err(err) => {
-            // ii. Perform ! Call(promiseCapability.[[Reject]], undefined, « result.[[Value]] »).
+            // ii. Perform ! Call(promiseCapability.[[Reject]], undefined, « result.[[Value]] »).
             global_state
                 .resolvers
                 .reject
@@ -610,7 +610,7 @@ fn from_array_like(
         Ok(cont) => Ok(cont),
         // i. Assert: result is a throw completion.
         Err(err) => {
-            // ii. Perform ! Call(promiseCapability.[[Reject]], undefined, « result.[[Value]] »).
+            // ii. Perform ! Call(promiseCapability.[[Reject]], undefined, « result.[[Value]] »).
             global_state
                 .resolvers
                 .reject

core/engine/src/module/mod.rs

@@ -658,6 +658,7 @@ impl Module {
                 None,
                 context,
             )
+            .expect("`then` cannot fail for a native `JsPromise`")
             .then(
                 Some(
                     NativeFunction::from_copy_closure_with_captures(
@@ -669,6 +670,7 @@ impl Module {
                 None,
                 context,
             )
+            .expect("`then` cannot fail for a native `JsPromise`")
     }
 
     /// Abstract operation [`GetModuleNamespace ( module )`][spec].

core/engine/src/module/synthetic.rs

@@ -257,8 +257,8 @@ impl SyntheticModule {
     ///
     /// [spec]: https://tc39.es/proposal-json-modules/#sec-smr-LoadRequestedModules
     pub(super) fn load(context: &mut Context) -> JsPromise {
-        // 1. Return ! PromiseResolve(%Promise%, undefined).
         JsPromise::resolve(JsValue::undefined(), context)
+            .expect("default resolve functions cannot throw and must return a promise")
     }
 
     /// Concrete method [`GetExportedNames ( [ exportStarSet ] )`][spec].