npm run build won't work

[tanepiper]

Run the following command and get the output below:

➜  mm-webcomponents git:(master) npm run build

> @stencil/[email protected] build /home/tane/work/mm-webcomponents
> stencil build --prerender

[50:24.8]  @stencil/core v0.0.9-4 
[50:24.8]  build, app, prod mode, started ... 
[50:24.8]  compile started ... 
[50:26.4]  compile finished in 1.67 s 
[50:26.4]  bundle styles started ... 
[50:26.4]  bundle modules started ... 
[50:26.5]  bundle styles finished in 85 ms 
[50:26.6]  bundle modules finished in 108 ms 
[50:26.6]  generate es2015 bundles started ... 
[50:26.6]  generate es2015 bundles finished in 71 ms 
[50:26.6]  generate es5 bundles started ... 
[50:26.7]  generate es5 bundles finished in 46 ms 
[50:28.4]  prerendering started ... 
[50:28.4]  prerender, started: / ... 
[50:28.7]  prerender, finished: / in 317 ms 
[50:28.8]  prerendered urls: 1 in 348 ms 
[50:28.8]  generate service worker started ... 
[50:28.8]  generate service worker finished in 32 ms 

[ ERROR ]  Runtime error detected during componentDidLoad(): mm-keyboard
           AudioContext is not defined 

[50:28.8]  build finished in 4.04 s

Tried to add @types/webaudioapi to the project, got lots of duplication errors.