How to use the graphql-transformer-core.TransformerContractError function in graphql-transformer-core

directiveList.forEach((value: DirectiveNode) => {
      const url = getDirectiveArgument(value, 'url');
      // require a protocol in the url
      const protocolMatcher = /^http(s)?:\/\//;
      if (!protocolMatcher.test(url)) {
        throw new TransformerContractError(
          `@http directive at location ${value.loc.start} ` + `requires a url parameter that begins with http:// or https://.`
        );
      }
      // extract just the base url with protocol
      const baseURL = url.replace(HttpTransformer.urlRegex, '$1');
      const dataSourceID = HttpResourceIDs.HttpDataSourceID(baseURL);
      // only create one DataSource per base URL
      if (!ctx.getResource(dataSourceID)) {
        ctx.mapResourceToStack(HTTP_STACK_NAME, dataSourceID);
        ctx.setResource(dataSourceID, this.resources.makeHttpDataSource(baseURL));
      }
    });
  };

let updatedFields = type.fields;
      const versionFieldImpl = type.fields.find(f => f.name.value === versionField);
      let updatedField = versionFieldImpl;
      if (versionFieldImpl) {
        const baseType = getBaseType(versionFieldImpl.type);
        if (baseType === 'Int' || baseType === 'BigInt') {
          // ok.
          if (versionFieldImpl.type.kind !== Kind.NON_NULL_TYPE) {
            updatedField = {
              ...updatedField,
              type: makeNonNullType(versionFieldImpl.type),
            };
            updatedFields = updatedFields.map(f => (f.name.value === versionField ? updatedField : f));
          }
        } else {
          throw new TransformerContractError(`The versionField "${versionField}" is required to be of type "Int" or "BigInt".`);
        }
      } else {
        updatedField = makeField(versionField, [], makeNonNullType(makeNamedType('Int')));
        updatedFields = [...updatedFields, updatedField];
      }
      const updatedType = {
        ...type,
        fields: updatedFields,
      };
      ctx.putType(updatedType);
    }
  }
}