Fix crash when a field has 'deprecated', but not 'description' (bcherny#549)

* Add failing test case

* Fix crash when deprecated is defined without description

* Add test case for bcherny#540 too

Author: danmichaelo

src/generator.ts

@@ -316,12 +316,14 @@ function generateInterface(ast: TInterface, options: Options): string {
   )
 }
 
-function generateComment(comment: string, deprecated?: boolean): string {
+function generateComment(comment?: string, deprecated?: boolean): string {
   const commentLines = ['/**']
   if (deprecated) {
     commentLines.push(' * @deprecated')
   }
-  commentLines.push(...comment.split('\n').map(_ => ' * ' + _))
+  if (typeof comment !== 'undefined') {
+    commentLines.push(...comment.split('\n').map(_ => ' * ' + _))
+  }
   commentLines.push(' */')
   return commentLines.join('\n')
 }

test/__snapshots__/test/test.ts.md

@@ -827,7 +827,6 @@ Generated by [AVA](https://avajs.dev).
     export interface ExampleSchema {␊
       /**␊
        * @deprecated␊
-       * nested comment␊
        */␊
       firstName: string;␊
       /**␊
@@ -839,6 +838,7 @@ Generated by [AVA](https://avajs.dev).
        * nested comment␊
        */␊
       lastName?: string;␊
+      description?: string;␊
     }␊
     `
 

test/__snapshots__/test/test.ts.snap

@@ -5,10 +5,10 @@ export const input = {
   deprecated: true,
   description: 'comment',
   properties: {
+    // https://github.com/bcherny/json-schema-to-typescript/issues/548
     firstName: {
       type: 'string',
       deprecated: true,
-      description: 'nested comment',
     },
     middleName: {
       type: 'string',
@@ -20,6 +20,10 @@ export const input = {
       deprecated: false,
       description: 'nested comment',
     },
+    // https://github.com/bcherny/json-schema-to-typescript/issues/540
+    description: {
+      type: 'string',
+    },
   },
   additionalProperties: false,
   required: ['firstName'],