test_runner: fix potential TypeError in junit reporter

The junit reporter could crash with a TypeError if a test event
was emitted without a `details` object. While `details` is common, its absence is a valid case that should not terminate the reporter.

Author: mete0rfish

lib/internal/test_runner/reporter/junit.js

@@ -103,7 +103,8 @@ module.exports = async function* junitReporter(source) {
         if (currentSuite?.nesting === event.data.nesting) {
           currentSuite = currentSuite.parent;
         }
-        currentTest.attrs.time = NumberPrototypeToFixed(event.data.details.duration_ms / 1000, 6);
+        const duration = event.data.details?.duration_ms ?? 0;
+        currentTest.attrs.time = NumberPrototypeToFixed(duration / 1000, 6);
         const nonCommentChildren = ArrayPrototypeFilter(currentTest.children, (c) => c.comment == null);
         if (nonCommentChildren.length > 0) {
           currentTest.tag = 'testsuite';