refactor: prevents a call to callback within try/catch block

lib/api/validate.js

@@ -11,15 +11,19 @@ function validate(real, expected, type, callback) {
     );
   }
 
+  let results;
+
   try {
-    const results = validateMessage(normalizedReal, normalizedExpected);
-    callback(null, {
-      version: '2',
-      ...results
-    });
+    results = validateMessage(normalizedReal, normalizedExpected);
   } catch (error) {
     callback(error, null);
+    return;
   }
+
+  callback(null, {
+    version: '2',
+    ...results
+  });
 }
 
 module.exports = validate;