[totally-not-ai]

Part of #26919

Behavior deviation · flow-server · apps using typed executeJs/callJsFunction results

When a typed JavaScript result can't be converted to the requested type (for example the browser returns "abc" for an Integer), the conversion error escaped the result handler. A typed toCompletableFuture(...) then never completed, so join()/get() hung and whenComplete callbacks never ran, and a typed then(..., errorHandler) threw instead of calling the error handler.

Risks:

• ⚠️ Behaviour change: a conversion error now goes to the error handler (or fails the future with JavaScriptException) instead of being thrown from the response handling; with no error handler it is logged as a warning.

• ⚠️ Behaviour change: JacksonCodec.decodeAs(JsonNode, Class) (internal) throws IllegalArgumentException instead of ClassCastException when the target is a JSON node type the value isn't.

• ✅ No public API change, no serialization or threading impact.

• Typed then(Class|TypeReference, …) decode inside a try and route IllegalArgumentException to the error handler; handlers added after it still run.

• Typed toCompletableFuture(Class|TypeReference) reuse the typed then, so conversion errors complete the future exceptionally.

• Exceptions thrown by the user's own result handler still propagate unchanged.

• decodeAs(JsonNode, Class) reports a node type mismatch (e.g. ObjectNode for an array) as IllegalArgumentException naming the node type.

The other part of the issue (aligning null-argument checks and JSON-null handling across the three decodeAs overloads) is left for after #26890, which touches the same code.

Fixes #26919

[github-actions]

Test Results

 1 677 files  ±0   1 766 suites  ±0   2h 8m 52s ⏱️ - 3m 51s
13 338 tests +6  13 270 ✅ +6  68 💤 ±0  0 ❌ ±0 
13 972 runs  +6  13 904 ✅ +6  68 💤 ±0  0 ❌ ±0 

Results for commit 76d78f7. ± Comparison against base commit a381afa.

♻️ This comment has been updated with latest results.

[totally-not-ai]

Added a Javadoc description to the new decodingHandler helper in PendingJavaScriptResult (S1176). The other 13 findings are on test code this PR doesn't change: the flagged lines in PendingJavaScriptInvocationTest (398–525) and JacksonCodecTest (373, 797) are existing tests whose line numbers only moved because of new imports or tests added above them. I left them as they are to keep this PR to one concern.

[sonarqubecloud]

Quality Gate passed

Issues
15 New issues
0 Accepted issues

Measures
0 Security Hotspots
96.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[totally-not-ai]

Documented the parameters and return value of the decodingHandler helper in PendingJavaScriptResult (S1176). The other findings are unchanged from the previous analysis: they are on existing test code in PendingJavaScriptInvocationTest and JacksonCodecTest that this PR doesn't modify, so they stay out of scope here.