stack trace: TypeError: Cannot read property 'dispose' of undefined    at /Users/danny/Dev/Dart-Code/src/extension/extension.ts:840:17    at Generator.next (<anonymous>)    at /Users/danny/Dev/Dart-Code/out/dist/extension.js:24638:71    at new Promise (<anonymous>)    at /Users/danny/Dev/Dart-Code/out/dist/extension.js:24634:12    at deactivate (/Users/danny/Dev/Dart-Code/out/dist/extension.js:25367:12)    at /Users/danny/Dev/Dart-Code/src/extension/extension.ts:153:9    at Generator.next (<anonymous>)    at /Users/danny/Dev/Dart-Code/out/dist/extension.js:24638:71    at new Promise (<anonymous>)    at /Users/danny/Dev/Dart-Code/out/dist/extension.js:24634:12    at /Users/danny/Dev/Dart-Code/src/extension/extension.ts:151:93    at _executeContributedCommand (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:694:793)    at _doExecuteCommand (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:693:978)    at _.executeCommand (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:693:884)    at Object.executeCommand (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:988:920)    at Object.<anonymous> (/Users/danny/Dev/Dart-Code/src/extension/utils.ts:237:13)    at Generator.next (<anonymous>)    at fulfilled (/Users/danny/Dev/Dart-Code/out/dist/extension.js:31484:58)    at processTicksAndRejections (internal/process/task_queues.js:94:5) (at /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:1059:700)