QMLJS: Fix exception handling in promises

If an exception is thrown inside a promise's resolve or reject
handler, the promise needs to resolve into a rejected state with the
exceptions value. The value was previously not set.

Fixes: QTBUG-78554
Change-Id: Ic22faa6ef1e519e4cae6732c69bb14f7053d13da
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlpromise/data/promisehandlerthrows.qml b/tests/auto/qml/qqmlpromise/data/promisehandlerthrows.qml
new file mode 100644
index 0000000000..d23ea43e74
--- /dev/null
+++ b/tests/auto/qml/qqmlpromise/data/promisehandlerthrows.qml
@@ -0,0 +1,17 @@
+import QtQuick 2.12
+
+Item {
+    id: root
+    property string errorMessage
+    Component.onCompleted: () => {
+    let prom = Promise.reject("Some error")
+        .then(
+                o => {console.log("Never reached");},
+                err => {
+                    console.log("Rethrowing err");
+                    throw err;
+                }
+             )
+        .catch(err => root.errorMessage = err)
+    }
+}