refactor(loadscript): add annotation & remove console error message

[jeff-tbd]

Self Checklist

• I wrote a PR title in English and added an appropriate label to the PR.
• I wrote the commit message in English and to follow the Conventional Commits specification.
• I wrote or updated documentation related to the changes. (or didn't have to)
• I wrote or updated tests related to the changes. (or didn't have to)
• I tested the changes in various browsers. (or didn't have to)
  • Windows: Chrome, Edge, (Optional) Firefox
  • macOS: Chrome, Edge, Safari, (Optional) Firefox
  • Android: Chrome, Samsung Internet
  • iOS: Safari, Chrome,

Related Issue

Summary

• refactor(loadscript): add annotation & remove console error message

Details

• If Channel SDK script is already loaded, this method does nothing.
• remove console error for loading twice

Breaking change? (Yes/No)

• No

References

• @see https://desk.channel.io/root/threads/groups/WebCellFront-115250/6513f80cd93ede69e599/651e403d4931cd3adcaf