UMD build doesn't work

[jasny]

When using the UMD build in Ownables SDK, we get the following error.

Failed to compile.

Module not found: Error: Can't resolve 'simple-iframe-rpc' in '/home/arnold/Projects/ltonetwork/ownables-sdk/src/components'
WARNING in ./node_modules/@scure/base/lib/index.js
Module Warning (from ./node_modules/source-map-loader/dist/cjs.js):
Failed to parse source map from '/home/arnold/Projects/ltonetwork/ownables-sdk/node_modules/@scure/base/lib/index.js.map' file: Error: ENOENT: no such file or directory, open '/home/arnold/Projects/ltonetwork/ownables-sdk/node_modules/@scure/base/lib/index.js.map'

ERROR in ./src/components/Ownable.tsx 7:0-69
Module not found: Error: Can't resolve 'simple-iframe-rpc' in '/home/arnold/Projects/ltonetwork/ownables-sdk/src/components'

ERROR in ./src/services/Ownable.service.ts 7:0-46
Module not found: Error: Can't resolve 'simple-iframe-rpc' in '/home/arnold/Projects/ltonetwork/ownables-sdk/src/services'

webpack compiled with 2 errors and 1 warning

Reverted back to AMD build for now.