Minor spelling mistake fixed.

Author: fecfecfec

src/content/8/en/part8c.md

@@ -158,7 +158,7 @@ Person.find({ phone: { $exists: false }})
 
 ### Validation
 
-As well as in GraphQL, the input is now validated using the validations defined in the mongoose schema. For handling possible validation errors in the schema, we must add an error-handling *try/catch* block to the *save* method. When we end up in the catch, we throw a exception [GraphQLError](https://www.apollographql.com/docs/apollo-server/data/errors/#custom-errors) with error code :
+As well as in GraphQL, the input is now validated using the validations defined in the mongoose schema. For handling possible validation errors in the schema, we must add an error-handling *try/catch* block to the *save* method. When we end up in the catch, we throw an exception [GraphQLError](https://www.apollographql.com/docs/apollo-server/data/errors/#custom-errors) with error code :
 
 ```js
 Mutation: {