message: Fix handling of periods in multiline warnings
  Attempting to print an undefined string will print 'undefined' not ''
diff: @@ -11,7 +11,7 @@ const latexError = /^(?:(.*):(\d+):|!)(?: (.+) Error:)? (.+?)$/
  const latexBox = /^((?:Over|Under)full \\[vh]box \([^)]*\)) in paragraph at lines (\d+)--(\d+)$/
  const latexBoxAlt = /^((?:Over|Under)full \\[vh]box \([^)]*\)) detected at line (\d+)$/
  const latexWarn = /^((?:(?:Class|Package) \S*)|LaTeX) (Warning|Info|Font Warning):\s+(.*?)(?: on input line (\d+))?(\.|\?|)$/
  -const latexPackageWarningExtraLines = /^\((.*)\)\s+(.*?)(?: on input line (\d+))?(\.)?$/
  +const latexPackageWarningExtraLines = /^\((.*)\)\s+(.*?)(?: +on input line (\d+))?(\.)?$/
  const bibEmpty = /^Empty `thebibliography' environment/
  const biberWarn = /^Biber warning:.*WARN - I didn't find a database entry for '([^']+)'/
  @@ -165,7 +165,7 @@ export class Parser {
  } else {
  const packageExtraLineResult = line.match(latexPackageWarningExtraLines)
  if (packageExtraLineResult) {
  - currentResult.text += '\n(' + packageExtraLineResult[1] + ')\t' + packageExtraLineResult[2] + packageExtraLineResult[4]
  + currentResult.text += '\n(' + packageExtraLineResult[1] + ')\t' + packageExtraLineResult[2] + (packageExtraLineResult[4] ? '.' : '')
  currentResult.line = parseInt(packageExtraLineResult[3], 10)
  } else if (insideError) {
  const subLine = line.replace(messageLine, '$1')
  