readline: set null as callback return in case there's no error

The cursor move functions accept a callback. It was possible that
`undefined` was returned in case there was no error instead of null.

PR-URL: #31006
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

lib/readline.js

@@ -1200,7 +1200,7 @@ function cursorTo(stream, x, y, callback) {
 
   if (stream == null || (typeof x !== 'number' && typeof y !== 'number')) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
@@ -1221,7 +1221,7 @@ function moveCursor(stream, dx, dy, callback) {
 
   if (stream == null || !(dx || dy)) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
@@ -1255,7 +1255,7 @@ function clearLine(stream, dir, callback) {
 
   if (stream === null || stream === undefined) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
@@ -1277,7 +1277,7 @@ function clearScreenDown(stream, callback) {
 
   if (stream === null || stream === undefined) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 

test/parallel/test-readline-csi.js

@@ -39,7 +39,9 @@ assert.throws(() => {
 }, /ERR_INVALID_CALLBACK/);
 
 // Verify that clearScreenDown() does not throw on null or undefined stream.
-assert.strictEqual(readline.clearScreenDown(null, common.mustCall()), true);
+assert.strictEqual(readline.clearScreenDown(null, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 assert.strictEqual(readline.clearScreenDown(undefined, common.mustCall()),
                    true);
 
@@ -67,7 +69,9 @@ assert.throws(() => {
 // Verify that clearLine() does not throw on null or undefined stream.
 assert.strictEqual(readline.clearLine(null, 0), true);
 assert.strictEqual(readline.clearLine(undefined, 0), true);
-assert.strictEqual(readline.clearLine(null, 0, common.mustCall()), true);
+assert.strictEqual(readline.clearLine(null, 0, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 assert.strictEqual(readline.clearLine(undefined, 0, common.mustCall()), true);
 
 // Nothing is written when moveCursor 0, 0
@@ -101,15 +105,19 @@ assert.throws(() => {
 // Verify that moveCursor() does not throw on null or undefined stream.
 assert.strictEqual(readline.moveCursor(null, 1, 1), true);
 assert.strictEqual(readline.moveCursor(undefined, 1, 1), true);
-assert.strictEqual(readline.moveCursor(null, 1, 1, common.mustCall()), true);
+assert.strictEqual(readline.moveCursor(null, 1, 1, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 assert.strictEqual(readline.moveCursor(undefined, 1, 1, common.mustCall()),
                    true);
 
 // Undefined or null as stream should not throw.
 assert.strictEqual(readline.cursorTo(null), true);
 assert.strictEqual(readline.cursorTo(), true);
 assert.strictEqual(readline.cursorTo(null, 1, 1, common.mustCall()), true);
-assert.strictEqual(readline.cursorTo(undefined, 1, 1, common.mustCall()), true);
+assert.strictEqual(readline.cursorTo(undefined, 1, 1, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 
 writable.data = '';
 assert.strictEqual(readline.cursorTo(writable, 'a'), true);