How to use the ono.ono.syntax function in ono

validateSchema(schema, parameterId, validTypes);
    validateRequiredPropertiesExist(schema, parameterId);

    if (schema.type === "file") {
      // "file" params must consume at least one of these MIME types
      let formData = /multipart\/(.*\+)?form-data/;
      let urlEncoded = /application\/(.*\+)?x-www-form-urlencoded/;

      let consumes = operation.consumes || api.consumes || [];

      let hasValidMimeType = consumes.some((consume) => {
        return formData.test(consume) || urlEncoded.test(consume);
      });

      if (!hasValidMimeType) {
        throw ono.syntax(
          `Validation failed. ${operationId} has a file parameter, so it must consume multipart/form-data ` +
          "or application/x-www-form-urlencoded",
        );
      }
    }
  }
}

try {
    let schema = await $RefParser.prototype.parse.call(this, args.path, args.schema, args.options);

    if (schema.swagger) {
      // Verify that the parsed object is a Swagger API
      if (schema.swagger === undefined || schema.info === undefined || schema.paths === undefined) {
        throw ono.syntax(`${args.path || args.schema} is not a valid Swagger API definition`);
      }
      else if (typeof schema.swagger === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('Swagger version number must be a string (e.g. "2.0") not a number.');
      }
      else if (typeof schema.info.version === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('API version number must be a string (e.g. "1.0.0") not a number.');
      }
      else if (schema.swagger !== "2.0") {
        throw ono.syntax(`Unrecognized Swagger version: ${schema.swagger}. Expected 2.0`);
      }
    }
    else {
      let supportedVersions = ["3.0.0", "3.0.1", "3.0.2"];

      // Verify that the parsed object is a Openapi API
      if (schema.openapi === undefined || schema.info === undefined || schema.paths === undefined) {
        throw ono.syntax(`${args.path || args.schema} is not a valid Openapi API definition`);
      }
      else if (typeof schema.openapi === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('Openapi version number must be a string (e.g. "3.0.0") not a number.');
      }

let operationParams = operation.parameters || [];

  // Check for duplicate path parameters
  try {
    checkForDuplicates(pathParams);
  }
  catch (e) {
    throw ono.syntax(e, `Validation failed. ${pathId} has duplicate parameters`);
  }

  // Check for duplicate operation parameters
  try {
    checkForDuplicates(operationParams);
  }
  catch (e) {
    throw ono.syntax(e, `Validation failed. ${operationId} has duplicate parameters`);
  }

  // Combine the path and operation parameters,
  // with the operation params taking precedence over the path params
  let params = pathParams.reduce((combinedParams, value) => {
    let duplicate = combinedParams.some((param) => {
      return param.in === value.in && param.name === value.name;
    });
    if (!duplicate) {
      combinedParams.push(value);
    }
    return combinedParams;
  }, operationParams.slice());

  validateBodyParameters(params, operationId);
  validatePathParameters(params, pathId, operationId);

function validatePathParameters (params, pathId, operationId) {
  // Find all {placeholders} in the path string
  let placeholders = pathId.match(util.swaggerParamRegExp) || [];

  // Check for duplicates
  for (let i = 0; i < placeholders.length; i++) {
    for (let j = i + 1; j < placeholders.length; j++) {
      if (placeholders[i] === placeholders[j]) {
        throw ono.syntax(
          `Validation failed. ${operationId} has multiple path placeholders named ${placeholders[i]}`);
      }
    }
  }

  params = params.filter((param) => { return param.in === "path"; });

  for (let param of params) {
    if (param.required !== true) {
      throw ono.syntax(
        "Validation failed. Path parameters cannot be optional. " +
        `Set required=true for the "${param.name}" parameter at ${operationId}`,
      );
    }
    let match = placeholders.indexOf("{" + param.name + "}");
    if (match === -1) {

SwaggerParser.prototype.parse = async function (path, api, options, callback) {
  let args = normalizeArgs(arguments);
  args.options = new Options(args.options);

  try {
    let schema = await $RefParser.prototype.parse.call(this, args.path, args.schema, args.options);

    if (schema.swagger) {
      // Verify that the parsed object is a Swagger API
      if (schema.swagger === undefined || schema.info === undefined || schema.paths === undefined) {
        throw ono.syntax(`${args.path || args.schema} is not a valid Swagger API definition`);
      }
      else if (typeof schema.swagger === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('Swagger version number must be a string (e.g. "2.0") not a number.');
      }
      else if (typeof schema.info.version === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('API version number must be a string (e.g. "1.0.0") not a number.');
      }
      else if (schema.swagger !== "2.0") {
        throw ono.syntax(`Unrecognized Swagger version: ${schema.swagger}. Expected 2.0`);
      }
    }
    else {
      let supportedVersions = ["3.0.0", "3.0.1", "3.0.2"];

throw ono.syntax('API version number must be a string (e.g. "1.0.0") not a number.');
      }
      else if (schema.swagger !== "2.0") {
        throw ono.syntax(`Unrecognized Swagger version: ${schema.swagger}. Expected 2.0`);
      }
    }
    else {
      let supportedVersions = ["3.0.0", "3.0.1", "3.0.2"];

      // Verify that the parsed object is a Openapi API
      if (schema.openapi === undefined || schema.info === undefined || schema.paths === undefined) {
        throw ono.syntax(`${args.path || args.schema} is not a valid Openapi API definition`);
      }
      else if (typeof schema.openapi === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('Openapi version number must be a string (e.g. "3.0.0") not a number.');
      }
      else if (typeof schema.info.version === "number") {
        // This is a very common mistake, so give a helpful error message
        throw ono.syntax('API version number must be a string (e.g. "1.0.0") not a number.');
      }
      else if (supportedVersions.indexOf(schema.openapi) === -1) {
        throw ono.syntax(
          `Unsupported OpenAPI version: ${schema.openapi}. ` +
          `Swagger Parser only supports versions ${supportedVersions.join(", ")}`
        );
      }
    }

    // Looks good!
    return maybe(args.callback, Promise.resolve(schema));
  }

}
      }
    }
    if (schemaObj.allOf) {
      for (let parent of schemaObj.allOf) {
        collectProperties(parent, props);
      }
    }
  }

  if (schema.required && Array.isArray(schema.required)) {
    let props = {};
    collectProperties(schema, props);
    for (let requiredProperty of schema.required) {
      if (!props[requiredProperty]) {
        throw ono.syntax(
          `Validation failed. Property '${requiredProperty}' listed as required but does not exist in '${schemaId}'`
        );
      }
    }
  }
}

function validateSchema (schema, schemaId, validTypes) {
  if (validTypes.indexOf(schema.type) === -1) {
    throw ono.syntax(
      `Validation failed. ${schemaId} has an invalid type (${schema.type})`);
  }

  if (schema.type === "array" && !schema.items) {
    throw ono.syntax(`Validation failed. ${schemaId} is an array, so it must include an "items" schema`);
  }
}

function validatePath (api, path, pathId, operationIds) {
  for (let operationName of swaggerMethods) {
    let operation = path[operationName];
    let operationId = pathId + "/" + operationName;

    if (operation) {
      let declaredOperationId = operation.operationId;
      if (declaredOperationId) {
        if (operationIds.indexOf(declaredOperationId) === -1) {
          operationIds.push(declaredOperationId);
        }
        else {
          throw ono.syntax(`Validation failed. Duplicate operation id '${declaredOperationId}'`);
        }
      }
      validateParameters(api, path, pathId, operation, operationId);

      let responses = Object.keys(operation.responses || {});
      for (let responseName of responses) {
        let response = operation.responses[responseName];
        let responseId = operationId + "/responses/" + responseName;
        validateResponse(responseName, (response || {}), responseId);
      }
    }
  }
}