TypeError: Cannot read property 'forEach' of undefined

[ronilaukkarinen]

I'm getting save action delays and noticed this in logs:

[15193:0722/122938.283400:INFO:CONSOLE(266)] "%c[Extension Host] %cLooking for parseable documents... %c(at log (/Users/rolle/Projects/vscode-settings/.vscode/extensions/gencer.html-slim-scss-css-class-completion-1.7.5/src/extension.ts:57:17)) color: blue color:  color: grey", source: file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js (266)
[15193:0722/122938.290652:INFO:CONSOLE(266)] "%c[Extension Host] %cFound all parseable documents. %c(at log (/Users/rolle/Projects/vscode-settings/.vscode/extensions/gencer.html-slim-scss-css-class-completion-1.7.5/src/extension.ts:72:17)) color: blue color:  color: grey", source: file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js (266)
[15193:0722/122938.290691:INFO:CONSOLE(266)] "%c[Extension Host] %cParsing documents and looking for CSS class definitions... %c(at log (/Users/rolle/Projects/vscode-settings/.vscode/extensions/gencer.html-slim-scss-css-class-completion-1.7.5/src/extension.ts:78:17)) color: blue color:  color: grey", source: file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js (266)
[15193:0722/122938.291370:INFO:CONSOLE(1670)] "%c  ERR color: #f33 Cannot read property 'forEach' of undefined: TypeError: Cannot read property 'forEach' of undefined
    at RunOnSaveExtension.runAllInTerminal (/Users/rolle/Projects/vscode-settings/.vscode/extensions/wk-j.save-and-run-0.0.21/out/src/runner.js:18:18)
    at RunOnSaveExtension.runCommands (/Users/rolle/Projects/vscode-settings/.vscode/extensions/wk-j.save-and-run-0.0.21/out/src/runner.js:111:14)
    at /Users/rolle/Projects/vscode-settings/.vscode/extensions/wk-j.save-and-run-0.0.21/out/src/extension.js:30:19
    at l.fire (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:45:801)
    at t.ExtHostDocuments.$acceptModelSaved (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:651:298)
    at m._doInvokeHandler (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:801:683)
    at m._invokeHandler (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:801:375)
    at m._receiveRequest (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:800:14)
    at m._receiveOneMessage (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:798:832)
    at /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:797:34
    at l.fire (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:45:801)
    at v.fire (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:235:849)
    at /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:975:744
    at l.fire (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:45:801)
    at v.fire (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:235:849)
    at t.PersistentProtocol._receiveMessage (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:240:276)
    at /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:237:357
    at l.fire (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:45:801)
    at p.acceptChunk (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:233:393)
    at /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:232:753
    at Socket.t (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/services/extensions/node/extensionHostProcess.js:241:826)
    at Socket.emit (events.js:203:13)
    at addChunk (_stream_readable.js:295:12)
    at readableAddChunk (_stream_readable.js:276:11)
    at Socket.Readable.push (_stream_readable.js:210:10)
    at Pipe.onStreamRead (internal/stream_base_commons.js:166:17)", source: file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js (1670)