message: Close Math preview also shows `flalign`
diff: @@ -9,7 +9,7 @@ export type TexMathEnv = { texString: string, range: vscode.Range, envname: stri
  export class TeXMathEnvFinder {
  findHoverOnTex(document: ITextDocumentLike, position: vscode.Position): TexMathEnv | undefined {
  - const envBeginPat = /\\begin\{(align|align\*|alignat|alignat\*|aligned|alignedat|array|Bmatrix|bmatrix|cases|CD|eqnarray|eqnarray\*|equation|equation\*|gather|gather\*|gathered|matrix|multline|multline\*|pmatrix|smallmatrix|split|subarray|Vmatrix|vmatrix)\}/
  + const envBeginPat = /\\begin\{(align|align\*|alignat|alignat\*|aligned|alignedat|array|Bmatrix|bmatrix|cases|CD|eqnarray|eqnarray\*|equation|equation\*|flalign|flalign\*|gather|gather\*|gathered|matrix|multline|multline\*|pmatrix|smallmatrix|split|subarray|Vmatrix|vmatrix)\}/
  let r = document.getWordRangeAtPosition(position, envBeginPat)
  if (r) {
  const envname = this.getFirstRememberedSubstring(document.getText(r), envBeginPat)
  @@ -32,7 +32,7 @@ export class TeXMathEnvFinder {
  ): TexMathEnv | undefined {
  const limit = vscode.workspace.getConfiguration('latex-workshop').get('hover.preview.maxLines') as number
  const docOfRef = TextDocumentLike.load(refData.file)
  - const envBeginPatMathMode = /\\begin\{(align|align\*|alignat|alignat\*|eqnarray|eqnarray\*|equation|equation\*|gather|gather\*)\}/
  + const envBeginPatMathMode = /\\begin\{(align|align\*|alignat|alignat\*|eqnarray|eqnarray\*|equation|equation\*|flalign|flalign\*|gather|gather\*)\}/
  const l = docOfRef.lineAt(refData.position.line).text
  const pat = new RegExp('\\\\label\\{' + utils.escapeRegExp(token) + '\\}')
  const m = l.match(pat)
  @@ -56,8 +56,8 @@ export class TeXMathEnvFinder {
  findMathEnvIncludingPosition(document: ITextDocumentLike, position: vscode.Position): TexMathEnv | undefined {
  const limit = vscode.workspace.getConfiguration('latex-workshop').get('hover.preview.maxLines') as number
  - const envNamePatMathMode = /(align|align\*|alignat|alignat\*|eqnarray|eqnarray\*|equation|equation\*|gather|gather\*)/
  - const envBeginPatMathMode = /\\\[|\\\(|\\begin\{(align|align\*|alignat|alignat\*|eqnarray|eqnarray\*|equation|equation\*|gather|gather\*)\}/
  + const envNamePatMathMode = /(align|align\*|alignat|alignat\*|eqnarray|eqnarray\*|equation|equation\*|flalign|flalign\*|gather|gather\*)/
  + const envBeginPatMathMode = /\\\[|\\\(|\\begin\{(align|align\*|alignat|alignat\*|eqnarray|eqnarray\*|equation|equation\*|flalign|flalign\*|gather|gather\*)\}/
  let texMath = this.findHoverOnTex(document, position)
  if (texMath && (texMath.envname === '$' || texMath.envname.match(envNamePatMathMode))) {
  return texMath
  