fix(core): use != to check if series is excluded as native map returns undefined rather than null

[plainheart]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

• fix: use != to check if series is excluded as native map returns undefined rather than null
• chore: use hasGlobalWindow constant from env util
• chore: use warn util instead of console.warn

Document Info

One of the following should be checked.

• This PR doesn't relate to document changes
• The document should be updated later
• The document changes have been made in apache/echarts-doc#xxx

Misc

ZRender Changes

• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

Please refer to test/area-stack.html

Others

Merging options

• Please squash the commits into a single one when merging.

Other information

[echarts-bot]

Thanks for your contribution!
The community will review it ASAP. In the meanwhile, please checkout the coding standard and Wiki about How to make a pull request.

The pull request is marked to be PR: author is committer because you are a committer of this project.

[echarts-bot]

Congratulations! Your PR has been merged. Thanks for your contribution! 👍