Uncaught TypeError: Cannot read property 'current' of undefined

[Enter steps to reproduce:]

1. ...
2. ...

**Atom**: 1.58.0 x64
**Electron**: 9.4.4
**OS**: Microsoft Windows 10 Home
**Thrown From**: [ide-python](https://github.com/lgeiger/ide-python) package 1.9.7

### Stack Trace

Uncaught TypeError: Cannot read property 'current' of undefined

```
At C:\Users\adghr\.atom\packages\ide-python\node_modules\react-dom\cjs\react-dom.production.min.js:250

TypeError: Cannot read property 'current' of undefined
at Pj (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:250:24)
at Tj (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:250:104)
at Lj (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:243:163)
at Jg (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:237:175)
at lk (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:285:27)
at /packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:289:301
at Xj (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:244:244)
at tk (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:289:287)
at Object.exports.render (/packages/ide-python/node_modules/react-dom/cjs/react-dom.production.min.js:296:69)
at HTMLElement.connectedCallback (/packages/atom-ide-debugger/node_modules/@atom-ide-community/nuclide-commons-ui/ReactMountRootElement.js:64:23)
at HTMLElement.activeItemChanged (/app.asar/src/pane-element.js:152:22)
at Function.simpleDispatch (~/AppData/Local/atom/app-1.58.0/resources/app/static/:11:1186925)
at Emitter.emit (~/AppData/Local/atom/app-1.58.0/resources/app/static/:11:1188366)
at Pane.setActiveItem (~/AppData/Local/atom/app-1.58.0/resources/app/static/:11:458925)
at Pane.activateItem (~/AppData/Local/atom/app-1.58.0/resources/app/static/:11:461173)
at DebuggerLayoutManager._appendItemToDock (/packages/atom-ide-debugger/dist/ui/DebuggerLayoutManager.js:323:20)
at DebuggerLayoutManager._addPaneContainerToWorkspace (/packages/atom-ide-debugger/dist/ui/DebuggerLayoutManager.js:648:10)
at DebuggerLayoutManager.showDebuggerViews (/packages/atom-ide-debugger/dist/ui/DebuggerLayoutManager.js:593:44)
at /packages/atom-ide-debugger/dist/main.js:412:24)
at CommandRegistry.handleCommandEvent (~/AppData/Local/atom/app-1.58.0/resources/app/static/:11:352326)
at CommandRegistry.dispatch (~/AppData/Local/atom/app-1.58.0/resources/app/static/:11:350801)
at BreakpointDisplayController._handleGutterClick (/packages/atom-ide-debugger/dist/BreakpointDisplayController.js:316:25)
```

### Commands

```
-1:55.1.0 core:paste (input.hidden-input)
8x -1:20.2.0 core:backspace (input.hidden-input)
-0:18.8.0 debugger:show (atom-workspace.workspace.scrollbars-visible-always.theme-one-dark-syntax.theme-one-dark-ui)
```

### Non-Core Packages

```
atom-ide-base 3.4.0
atom-ide-code-format 1.0.2
atom-ide-console 0.0.2
atom-ide-datatip 0.25.0
atom-ide-debugger 0.0.3
atom-ide-definitions 0.4.2
atom-ide-hyperclick 1.0.11
atom-ide-markdown-service 2.1.0
atom-ide-outline 3.2.0
atom-ide-signature-help 0.16.0
atom-material-ui 2.1.3
atom-python-run 0.9.7
busy-signal 2.0.1
Hydrogen 2.16.3
ide-python 1.9.7
intentions 2.1.1
linter 3.4.0
linter-ui-default 3.4.1
python-tools 0.6.9
script 3.32.2
zentabs 0.8.9
```

Start by reproducing the error with the reported debugger:show command after a gutter click, then trace the stack through DebuggerLayoutManager._appendItemToDock and ReactMountRootElement.js:64. Compare the installed ide-python, atom-ide-debugger, and React versions; done means the debugger view opens without the uncaught TypeError under the reported environment.

Written by the indexing model from the issue text.