fix(ses): fix 2943 error trapping issues

packages/ses/error-codes/SES_UNCAUGHT_EXCEPTION.md

@@ -6,6 +6,8 @@ This behavior is configured by calling `lockdown` with the [errorTrapping][] opt
 
 Otherwise, when thrown exceptions have no `catch` handler, the SES shim will print `SES_UNCAUGHT_EXCEPTION: exception...` to the error console.  In that case, `exception...` is the thrown exception, augmented with causal error information when possible.
 
+On some platforms, the default errorTrapping behavior reports the error, but the platform's user trapping mechanism reports only an event with no error. (See https://github.com/endojs/endo/issues/2941 test1.) In that case, non-default `errorTrapping` reports the event about the error, rather than the error itself. This often has much less relevant information than the (inaccessible) error would, but is better than nothing.
+
 For most programs, the error console is intended for human consumption, and so the `SES_UNCAUGHT_EXCEPTION:` output can be useful in giving a clue as to the source of a failure.
 
 [errorTrapping]: ../docs/lockdown.md#errortrapping-options

packages/ses/src/error/tame-console.js

@@ -156,7 +156,7 @@ export const tameConsole = (
     globalWindow.addEventListener('error', event => {
       event.preventDefault();
       // See https://github.com/endojs/endo/blob/master/packages/ses/error-codes/SES_UNCAUGHT_EXCEPTION.md
-      ourConsole.error('SES_UNCAUGHT_EXCEPTION:', event.error);
+      ourConsole.error('SES_UNCAUGHT_EXCEPTION:', event.error ?? event);
       // 'platform' and 'report' just log the reason.
       if (errorTrapping === 'exit' || errorTrapping === 'abort') {
         globalWindow.location.href = `about:blank`;