aio app:deploy error if static project contains files with .mst extension

[mhaack]

Describe the bug
A static project containing .mst files (mustache templates) can not be deployed. Debug log:

Deploying actions
⠋ Deploying web assets  @adobe/aio-lib-core-tvm:debug initializing with config: {
  @adobe/aio-lib-core-tvm:debug   "ow": {
  @adobe/aio-lib-core-tvm:debug     "namespace": "278519-mhtest-stage",
  @adobe/aio-lib-core-tvm:debug     "auth": "<hidden>"
  @adobe/aio-lib-core-tvm:debug   },
  @adobe/aio-lib-core-tvm:debug   "apiUrl": "https://firefly-tvm.adobe.io",
  @adobe/aio-lib-core-tvm:debug   "cacheFile": "/Users/mhaack/workspaces/playground/aio-pwa/.aws.tmp.creds.json"
  @adobe/aio-lib-core-tvm:debug }
  @adobe/aio-lib-core-tvm:debug read credentials from cache file with key b96338bb5bc5e6512bd5f8cf241b7168c3d302052818878a5188b8797fc8ef5c
TypeError: mimeType.startsWith is not a function
    at RemoteStorage._getCacheControlConfig (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@adobe/aio-lib-web/lib/remote-storage.js:179:25)
    at RemoteStorage.uploadFile (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@adobe/aio-lib-web/lib/remote-storage.js:110:37)
    at async /Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@adobe/aio-lib-web/lib/remote-storage.js:157:21
    at async Promise.all (index 42)
    at async Object.deployWeb (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@adobe/aio-lib-web/src/deploy-web.js:58:3)
    at async Deploy.run (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@adobe/aio-cli-plugin-app/src/commands/app/deploy.js:108:35)
    at async Deploy._run (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@oclif/command/lib/command.js:43:20)
    at async Config.runCommand (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@oclif/config/lib/config.js:173:24)
    at async Main.run (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@oclif/command/lib/main.js:27:9)
    at async Main._run (/Users/mhaack/.nvm/versions/node/v12.13.0/lib/node_modules/@adobe/aio-cli/node_modules/@oclif/command/lib/command.js:43:20)

Sample files can be found here: https://github.com/magento/pwa-studio/tree/develop/packages/venia-ui/templates

Expected behavior
Deployment is working.

Additional context
aio cli version:

System:
    OS: macOS 10.15.7
    CPU: (12) x64 Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
    Memory: 441.09 MB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 12.13.0 - ~/.nvm/versions/node/v12.13.0/bin/node
    Yarn: 1.22.0 - /usr/local/bin/yarn
    npm: 6.12.0 - ~/.nvm/versions/node/v12.13.0/bin/npm
  Virtualization:
    Docker: 19.03.13 - /usr/local/bin/docker
  npmGlobalPackages:
    @adobe/aio-cli: 5.0.1
  CLI plugins:
    @adobe/aio-cli 5.0.1 (core)
    @adobe/aio-cli-plugin-app 5.2.1 (core)
    @adobe/aio-cli-plugin-auth 2.4.0 (core)
    @adobe/aio-cli-plugin-certificate 0.2.0 (core)
    @adobe/aio-cli-plugin-cloudmanager 0.18.2 (user)
    @adobe/aio-cli-plugin-config 2.3.0 (core)
    @adobe/aio-cli-plugin-console 3.2.0 (core)
    @adobe/aio-cli-plugin-events 1.1.0 (core)
    @adobe/aio-cli-plugin-info 1.1.1 (core)
    @adobe/aio-cli-plugin-runtime 3.0.0 (core)
    @oclif/plugin-autocomplete 0.2.0 (core)
    @oclif/plugin-help 2.2.3 (core)
    @oclif/plugin-not-found 1.2.4 (core)
    @oclif/plugin-plugins 1.9.4 (core)
    @oclif/plugin-warn-if-update-available 1.7.0 (core)

[meryllblanchet]

Thanks for raising the issue @mhaack!
@purplecabbage would there be any workaround while we'd work on the resolution?

[moritzraho]

some more details on the probable cause:

• The error is thrown from https://github.com/adobe/aio-lib-web/blob/master/lib/remote-storage.js#L179 because of the fact that we don't handle the case when mime.lookup(extname) (https://github.com/adobe/aio-lib-web/blob/master/lib/remote-storage.js#L109) returns false
• We should support a default mime type

[aiojbot]

JIRA issue created: https://jira.corp.adobe.com/browse/ACNA-967

[purplecabbage]

This is a problem with how we treat false/missing values returned by https://www.npmjs.com/package/mime-types

[aiojbot]

JIRA issue created: https://jira.corp.adobe.com/browse/ACNA-995