module: ignore resolution failures for inspect-brk

The resolution for the main entry point may fail when the resolution
requires a preloaded module to be executed first (for example when
adding new extensions to the resolution process). Silently skipping
such failures allow us to defer the resolution as long as needed
without having any adverse change (since the main entry point won't
resolve anyway if it really can't be resolved at all).

Author: arcanis

lib/internal/modules/cjs/loader.js

@@ -1091,14 +1091,17 @@ Module.prototype._compile = function(content, filename) {
     if (!resolvedArgv) {
       // We enter the repl if we're not given a filename argument.
       if (process.argv[1]) {
-        resolvedArgv = Module._resolveFilename(process.argv[1], null, false);
+        // The resolution may fail if it requires a preload script
+        try {
+          resolvedArgv = Module._resolveFilename(process.argv[1], null, false);
+        } catch {}
       } else {
         resolvedArgv = 'repl';
       }
     }
 
     // Set breakpoint on module start
-    if (!hasPausedEntry && filename === resolvedArgv) {
+    if (resolvedArgv && !hasPausedEntry && filename === resolvedArgv) {
       hasPausedEntry = true;
       inspectorWrapper = internalBinding('inspector').callAndPauseOnStart;
     }

test/fixtures/test-resolution-inspect-brk-main.ext

@@ -0,0 +1,5 @@
+'use strict';
+// eslint-disable-next-line no-unused-vars
+const common = require('../common');
+
+require.extensions['.ext'] = require.extensions['.js'];

test/fixtures/test-resolution-inspect-brk-resolver.js

@@ -0,0 +1,29 @@
+'use strict';
+const common = require('../common');
+common.skipIfInspectorDisabled();
+
+// A test to ensure that preload modules are given a chance to execute before
+// resolving the main entry point with --inspect-brk active.
+
+const assert = require('assert');
+const cp = require('child_process');
+const path = require('path');
+
+function test(execArgv) {
+  const child = cp.spawn(process.execPath, execArgv);
+
+  child.stderr.once('data', common.mustCall(function() {
+    child.kill('SIGTERM');
+  }));
+
+  child.on('exit', common.mustCall(function(code, signal) {
+    assert.strictEqual(signal, 'SIGTERM');
+  }));
+}
+
+test([
+  '--require',
+  path.join(__dirname, '../fixtures/test-resolution-inspect-brk-resolver.js'),
+  '--inspect-brk',
+  '../fixtures/test-resolution-inspect-resolver-main.ext',
+]);