react-docgen-typescript: Cannot read property 'length' of undefined

[hazem3500]

Describe the bug
In storybook, I get the error

70% sealing React Docgen Typescript Plugin __PATH__\node_modules\react-docgen-typescript\lib\parser.js:577
            if (functionStatement && functionStatement.parameters.length) {
                                                                  ^

TypeError: Cannot read property 'length' of undefined

my typescript version is 4.2.4

System
Environment Info:

System:
OS: Windows 10 10.0.18362
CPU: (4) x64 Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz
Binaries:
Node: 14.8.0 - C:\Program Files\nodejs\node.EXE
Yarn: 1.22.4 - C:\Program Files\nodejs\yarn.CMD
npm: 6.14.7 - C:\Program Files\nodejs\npm.CMD
Browsers:
Chrome: 91.0.4472.77
Edge: Spartan (44.18362.449.0)
npmPackages:
@storybook/addon-a11y: ^6.1.9 => 6.2.9
@storybook/addon-essentials: ^6.1.9 => 6.2.9
@storybook/preset-typescript: ^3.0.0 => 3.0.0
@storybook/react: ^6.1.6 => 6.2.9

[shilman]

Try removing preset-typescript. Typescript support is built-in after SB6.0.

Also, can you please create a reproduction by running npx sb@next repro, following the instructions, and linking it in your issue description? We prioritize issues with reproductions over those without. Thank you! 🙏

[hazem3500]

While I couldn't isolate the problem to create a reproduction, I've used patch-package to make a monkey patch for react-docgen-typescript that solved the problem.

I've changed the line

if (functionStatement && functionStatement.parameters.length)

to

if (functionStatement && functionStatement.parameters && functionStatement.parameters.length)

Monkey Patch

diff --git a/node_modules/react-docgen-typescript/lib/parser.js b/node_modules/react-docgen-typescript/lib/parser.js
  index d24f3c8..fe1ab44 100644
  --- a/node_modules/react-docgen-typescript/lib/parser.js
  +++ b/node_modules/react-docgen-typescript/lib/parser.js
  @@ -574,7 +574,7 @@ var Parser = /** @class */ (function () {
               }
               var functionStatement = _this.getFunctionStatement(statement);
               // Extracting default values from props destructuring
  -            if (functionStatement && functionStatement.parameters.length) {
  +            if (functionStatement && functionStatement.parameters && functionStatement.parameters.length) {
                   var name = functionStatement.parameters[0].name;
                   if (ts.isObjectBindingPattern(name)) {
                       return __assign({}, res, _this.getPropMap(name.elements));

I've made a PR in react-docgen-typescript to solve the issue

[hazem3500]

Closed as PR is merged in react-docgen-typescript