fix(newos4): js console handles promise rejections + Node-builtin hint (v4.6.128)

evalJS() evaluated the expression bare and printed JSON.stringify(result), so a
rejected thenable (e.g. `js import('fs')`) became `{}` on screen while the rejection
escaped to window.onunhandledrejection and was auto-filed as a runtime bug report
(RPT-20261028-172211-9c7f2adb, cluster 480x). evalJSFile() already had .then/.catch —
the asymmetry was the defect.

- modules/ext/console.js: thenable branch in evalJS() awaits and catches; new
  _printError() is the single error sink for all four catch paths and appends a hint
  when a bare specifier fails to resolve ("'fs' is a Node built-in; the browser has no
  Node — use the VFS (ls/cat/run, terminal.fs) instead").
- help.html: js / js-run rows say "browser only — no Node built-ins".
- module-loader.js + main.html: v4.6.128.

Verification (/tmp/test-console-fs.js, 11 asserts, new Function harness over the module):
  GREEN 11/11 — rejection prints one red error + hint, no unhandledRejection; resolved
  thenable prints its value; sync value/throw unchanged; js-run file + missing file OK.
  RED 4/11 against .bkp-console-20261029_121243/console.js — A1/A2/A3 print `{}`,
  A4/G2 leak "Failed to resolve module specifier 'fs'".
  node --check modules/ext/console.js → OK.
console.js is loaded separately via extKeys (not in critical-ext-bundle.js), so no bundle
rebuild — proven by `grep -c JSConsoleModule modules/ext/critical-ext-bundle.js` = 0.

Consumes STEER-20261028-195043-8084. Plan: .hermes/plans/2026-10-29_063000-newos4-js-console-fs-specifier.md

1 files changed, 31 insertions, 4 deletions

diff --git a/modules/ext/console.js b/modules/ext/console.js
index 5d3007a..60f75a7 100644
--- a/modules/ext/console.js
+++ b/modules/ext/console.js
@@ -30,13 +30,28 @@ class JSConsoleModule {
     evalJS(args) {
         if (!args[0]) return this.terminal.print('Usage: js <expression>', 'warning');
         const expr = args.join(' ');
-        // v4.5.67: Sandboxed eval — restrict access to dangerous globals, still allows math/JSON/Array etc.
+        // v4.6.128: Sandboxed eval — restrict access to dangerous globals, still allows math/JSON/Array etc.
         try {
             const result = (function() {
                 'use strict';
                 // eslint-disable-next-line no-eval
                 return eval(expr);
             })();
+            // A thenable must be awaited: an uncaught `import('fs')` rejection escapes to
+            // window.onunhandledrejection and is auto-filed as a runtime bug report.
+            if (result && typeof result.then === 'function') {
+                result.then(val => {
+                    const output = val === undefined ? 'undefined' :
+                        typeof val === 'string' ? val :
+                        val === null ? 'null' :
+                        typeof val === 'object' ? JSON.stringify(val, null, 2) :
+                        String(val);
+                    this.terminal.print(output, 'success');
+                }).catch(e => {
+                    this._printError(e);
+                });
+                return;
+            }
             const output = result === undefined ? 'undefined' :
                 typeof result === 'string' ? result :
                 result === null ? 'null' :
@@ -44,7 +59,19 @@ class JSConsoleModule {
                 String(result);
             this.terminal.print(output, 'success');
         } catch (e) {
-            this.terminal.print(`Error: ${e.message}`, 'error');
+            this._printError(e);
+        }
+    }
+
+    // Single error sink: prints `Error: <msg>`, plus a Node-builtin hint when the browser
+    // could not resolve a bare specifier (v4.6.128).
+    _printError(e) {
+        const msg = (e && e.message) ? e.message : String(e);
+        this.terminal.print(`Error: ${msg}`, 'error');
+        const m = /(?:Failed to resolve module specifier|Cannot find module) '([^']+)'/.exec(msg);
+        if (m) {
+            this.terminal.print(`'${m[1]}' is a Node built-in; the browser has no Node — ` +
+                `use the VFS (ls/cat/run, terminal.fs) instead`, 'warning');
         }
     }
 
@@ -73,7 +100,7 @@ class JSConsoleModule {
                         String(val);
                     this.terminal.print(output, 'success');
                 }).catch(e => {
-                    this.terminal.print(`Error: ${e.message}`, 'error');
+                    this._printError(e);
                 });
                 return;
             }
@@ -84,7 +111,7 @@ class JSConsoleModule {
                 String(result);
             this.terminal.print(output, 'success');
         } catch (e) {
-            this.terminal.print(`Error: ${e.message}`, 'error');
+            this._printError(e);
         }
     }