message: Use import type.
diff: import * as vscode from 'vscode'
  import * as path from 'path'
  -import {MathPreview, TexMathEnv} from '../providers/preview/mathpreview'
  +import type {MathPreview, TexMathEnv} from '../providers/preview/mathpreview'
  import {openWebviewPanel} from '../utils/webview'
  import type {Extension} from '../main'
  