fix(docgen): Vue.extends without comments

closes #1027

packages/vue-docgen-api/src/script-handlers/__tests__/componentHandler.ts

@@ -165,4 +165,31 @@ describe('componentHandler', () => {
 		}
 		expect(documentation.set).toHaveBeenCalledWith('description', 'Best Button Ever')
 	})
+
+	it('should extract all info when Vue.extends is assigned to a const and exported later', () => {
+		const src = `
+	/**
+	 * @displayName Best Button Ever
+	 */
+    const button = Vue.extends({
+	})
+
+	export default button
+    `
+		const def = parse(src).get('default')
+		if (def) {
+			componentHandler(documentation, def)
+		}
+		expect(documentation.set).toHaveBeenCalledWith('displayName', 'Best Button Ever')
+	})
+
+	it('should not fail when no comments are on a Vue.extends', () => {
+		const src = `export default Vue.extends({})`
+		const def = parse(src).get('default')
+		expect(() => {
+			if (def) {
+				componentHandler(documentation, def)
+			}
+		}).not.toThrow()
+	})
 })

packages/vue-docgen-api/src/script-handlers/componentHandler.ts

@@ -29,7 +29,11 @@ export default function propHandler(documentation: Documentation, path: NodePath
 	if (bt.isCallExpression(componentCommentedPath.node)) {
 		// look for leading comments in the parent structures
 		let i = 5
-		while (i-- && !componentCommentedPath.get('leadingComments').value) {
+		while (
+			i-- &&
+			!componentCommentedPath.get('leadingComments').value &&
+			componentCommentedPath.parentPath.node.type !== 'Program'
+		) {
 			componentCommentedPath = componentCommentedPath.parentPath
 		}
 	} else if (bt.isVariableDeclarator(componentCommentedPath.node)) {