fs: do not call Dir read callback twice

lib/internal/fs/dir.js

@@ -130,21 +130,22 @@ class Dir {
     }
 
     if (this.#processHandlerQueue()) {
+      let dirent;
       try {
-        const dirent = ArrayPrototypeShift(this.#bufferedEntries);
+        dirent = ArrayPrototypeShift(this.#bufferedEntries);
 
         if (this.#options.recursive && dirent.isDirectory()) {
           this.#readSyncRecursive(dirent);
         }
-
-        if (maybeSync)
-          process.nextTick(callback, null, dirent);
-        else
-          callback(null, dirent);
-        return;
       } catch (error) {
         return callback(error);
       }
+
+      if (maybeSync)
+        process.nextTick(callback, null, dirent);
+      else
+        callback(null, dirent);
+      return;
     }
 
     const req = new FSReqCallback();
@@ -159,16 +160,17 @@ class Dir {
         return callback(err, result);
       }
 
+      let dirent;
       try {
         this.#processReadResult(this.#path, result);
-        const dirent = ArrayPrototypeShift(this.#bufferedEntries);
+        dirent = ArrayPrototypeShift(this.#bufferedEntries);
         if (this.#options.recursive && dirent.isDirectory()) {
           this.#readSyncRecursive(dirent);
         }
-        callback(null, dirent);
       } catch (error) {
-        callback(error);
+        return callback(error);
       }
+      callback(null, dirent);
     };
 
     this.#operationQueue = [];

test/parallel/test-fs-opendir-read-callback-throw.js

@@ -0,0 +1,31 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const fs = require('fs');
+const tmpdir = require('../common/tmpdir');
+
+tmpdir.refresh();
+
+const dir = tmpdir.resolve('opendir-cb-throw');
+fs.mkdirSync(dir);
+fs.writeFileSync(`${dir}/a.txt`, '');
+fs.writeFileSync(`${dir}/b.txt`, '');
+
+// `dir.read(callback)` used to invoke `callback` from inside a `try` block, so
+// an exception thrown by user code inside the callback was caught and fed back
+// into the same callback as if it were a directory read failure. The callback
+// must be invoked exactly once, and only with the result of the read.
+
+process.on('uncaughtException', (err) => {
+  assert.strictEqual(err.message, 'thrown from the read callback');
+});
+
+fs.opendir(dir, common.mustSucceed((d) => {
+  d.read(common.mustCall((err, dirent) => {
+    assert.strictEqual(err, null);
+    assert.notStrictEqual(dirent, null);
+    assert.match(dirent.name, /^[ab]\.txt$/);
+    throw new Error('thrown from the read callback');
+  }, 1));
+}));