errors: remove dead code

This was never falsy, since an array length can only be an integer.

PR-URL: #20483
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>

lib/internal/errors.js

@@ -870,7 +870,6 @@ E('ERR_INVALID_ARG_VALUE', (name, value, reason = 'is invalid') => {
 }, TypeError, RangeError);
 E('ERR_INVALID_ARRAY_LENGTH',
   (name, len, actual) => {
-    internalAssert(typeof actual === 'number', 'actual must be of type number');
     return `The array "${name}" (length ${actual}) must be of length ${len}.`;
   }, TypeError);
 E('ERR_INVALID_ASYNC_ID', 'Invalid %s value: %s', RangeError);