[jsinterp] Handle `NaN` in bitwise operators

Closes #6131

test/test_jsinterp.py

@@ -445,6 +445,16 @@ class TestJSInterpreter(unittest.TestCase):
         jsi = JSInterpreter('function x(){return 1236566549 << 5}')
         self.assertEqual(jsi.call_function('x'), 915423904)
 
+    def test_bitwise_operators_typecast(self):
+        jsi = JSInterpreter('function x(){return null << 5}')
+        self.assertEqual(jsi.call_function('x'), 0)
+
+        jsi = JSInterpreter('function x(){return undefined >> 5}')
+        self.assertEqual(jsi.call_function('x'), 0)
+
+        jsi = JSInterpreter('function x(){return 42 << NaN}')
+        self.assertEqual(jsi.call_function('x'), 42)
+
     def test_negative(self):
         jsi = JSInterpreter("function f(){return 2    *    -2.0;}")
         self.assertEqual(jsi.call_function('f'), -4)

test/test_youtube_signature.py

@@ -146,6 +146,10 @@ _NSIG_TESTS = [
         'https://www.youtube.com/s/player/6f20102c/player_ias.vflset/en_US/base.js',
         'lE8DhoDmKqnmJJ', 'pJTTX6XyJP2BYw',
     ),
+    (
+        'https://www.youtube.com/s/player/cfa9e7cb/player_ias.vflset/en_US/base.js',
+        'aCi3iElgd2kq0bxVbQ', 'QX1y8jGb2IbZ0w',
+    ),
 ]
 
 

yt_dlp/jsinterp.py

@@ -20,7 +20,12 @@ from .utils import (
 
 def _js_bit_op(op):
     def zeroise(x):
-        return 0 if x in (None, JS_Undefined) else x
+        if x in (None, JS_Undefined):
+            return 0
+        with contextlib.suppress(TypeError):
+            if math.isnan(x):  # NB: NaN cannot be checked by membership
+                return 0
+        return x
 
     def wrapped(a, b):
         return op(zeroise(a), zeroise(b)) & 0xffffffff