test: simplify common.expectsError

The mustCall is actually only necessary in case it is used as
callback. Otherwise it works as a must call on its own.

PR-URL: nodejs#17616
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>

test/common/index.js

@@ -735,7 +735,7 @@ exports.expectsError = function expectsError(fn, settings, exact) {
     settings = fn;
     fn = undefined;
   }
-  const innerFn = exports.mustCall(function(error) {
+  function innerFn(error) {
     assert.strictEqual(error.code, settings.code);
     if ('type' in settings) {
       const type = settings.type;
@@ -768,12 +768,12 @@ exports.expectsError = function expectsError(fn, settings, exact) {
       });
     }
     return true;
-  }, exact);
+  }
   if (fn) {
     assert.throws(fn, innerFn);
     return;
   }
-  return innerFn;
+  return exports.mustCall(innerFn, exact);
 };
 
 exports.skipIfInspectorDisabled = function skipIfInspectorDisabled() {