tls: use validateFunction for options.SNICallback

If user uses invalid type for `options.SNICallback` in
TLSSocket(), it's not internal issue of Node.js. So
validateFunction() is more proper than assert().

PR-URL: nodejs#50530
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/_tls_wrap.js

@@ -909,7 +909,7 @@ TLSSocket.prototype._init = function(socket, wrap) {
       options.SNICallback &&
       (options.SNICallback !== SNICallback ||
        (options.server && options.server._contexts.length))) {
-    assert(typeof options.SNICallback === 'function');
+    validateFunction(options.SNICallback, 'options.SNICallback');
     this._SNICallback = options.SNICallback;
     ssl.enableCertCb();
   }

test/parallel/test-tls-snicallback-error.js

@@ -4,11 +4,21 @@ if (!common.hasCrypto)
   common.skip('missing crypto');
 
 const assert = require('assert');
+const net = require('net');
 const tls = require('tls');
 
-['fhqwhgads', 42, {}, []].forEach((testValue) => {
-  assert.throws(
-    () => { tls.createServer({ SNICallback: testValue }); },
-    { code: 'ERR_INVALID_ARG_TYPE', message: /\boptions\.SNICallback\b/ }
-  );
-});
+for (const SNICallback of ['fhqwhgads', 42, {}, []]) {
+  assert.throws(() => {
+    tls.createServer({ SNICallback });
+  }, {
+    code: 'ERR_INVALID_ARG_TYPE',
+    name: 'TypeError',
+  });
+
+  assert.throws(() => {
+    new tls.TLSSocket(new net.Socket(), { isServer: true, SNICallback });
+  }, {
+    code: 'ERR_INVALID_ARG_TYPE',
+    name: 'TypeError',
+  });
+}