babel-plugin-flow-runtime references undefined type parameter names with assertions disabled

[](https://oss.issuehunt.io/r/gajus/flow-runtime/issues/180)

This is a:

- [x] Bug Report
- [ ] Feature Request
- [ ] Question
- [ ] Other

Which concerns:

- [ ] flow-runtime
- [x] babel-plugin-flow-runtime
- [ ] flow-runtime-validators
- [ ] flow-runtime-mobx
- [ ] flow-config-parser
- [ ] The documentation website

---

### Code

```js
// @flow

function foo() {
let bar: X
}
```
### `.babelrc`
```
{
"presets": ["es2015"],
"plugins": [
"transform-decorators-legacy",
["flow-runtime", {"assert": false}]
]
}
```

### What is the current behaviour?

---
`X` is undefined in the output code below at `let _barType = X`:
```js
import t from "flow-runtime";
function foo() {
let _barType = X,
bar;
}
t.annotate(foo, t.function(_fn => {
const X = _fn.typeParameter("X");

return [];
}));
```

### What is the expected behaviour?

---
Either `babel-plugin-flow-runtime` doesn't create `_barType`, or it inserts `const X = t.typeParameter("X")` above `let _barType` it despite the `"assert": false` in the plugin options.

### Which package versions are you using?

```
├── babel-core@6.26.0
├── babel-plugin-flow-runtime@0.15.0
├── babel-preset-es2015@6.24.0
```

---

IssueHunt Summary

### Backers (Total: $40.00)

- [ issuehunt](https://oss.issuehunt.io/u/issuehunt) ($40.00)

### Submitted pull Requests
- [#285 Fix assert false type parameter variables](https://oss.issuehunt.io/r/gajus/flow-runtime/pull/285)
- [#296 fix(plugin): avoid undefined type parameter references when assert=false](https://oss.issuehunt.io/r/gajus/flow-runtime/pull/296)
---

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Start with the provided babel-plugin-flow-runtime reproduction: transform the generic foo function using assert:false and inspect the generated code around the bar annotation. Compare the result with pull requests #285 and #296; done means the output no longer references X before it is defined or omits the unnecessary type variable.

Written by the indexing model from the issue text.