message: Fix popup severity
  Here is the conversion table used between the exit status of spawn
  and the popup severity
  fatal error  -> error
  error  -> warning
  anything else  -> info
  Related to
diff: @@ -107,7 +107,7 @@ export class Builder {
  this.currentProcess.on('error', err => {
  this.extension.logger.addLogMessage(`Build fatal error: ${err.message}, ${stderr}. PID: ${pid}. Does the executable exist?`)
  - this.extension.logger.displayStatus('x', 'errorForeground', `Build terminated with fatal error: ${err.message}.`)
  + this.extension.logger.displayStatus('x', 'errorForeground', `Build terminated with fatal error: ${err.message}.`, 'error')
  this.currentProcess = undefined
  releaseBuildMutex()
  })
  @@ -116,7 +116,7 @@ export class Builder {
  this.extension.logParser.parse(stdout)
  if (exitCode !== 0) {
  this.extension.logger.addLogMessage(`Build returns with error: ${exitCode}/${signal}. PID: ${pid}.`)
  - this.extension.logger.displayStatus('x', 'errorForeground', 'Build terminated with error')
  + this.extension.logger.displayStatus('x', 'errorForeground', 'Build terminated with error', 'warning')
  const res = this.extension.logger.showErrorMessage('Build terminated with error.', 'Open compiler log')
  if (res) {
  res.then(option => {
  @@ -281,7 +281,7 @@ export class Builder {
  this.currentProcess.on('error', err => {
  this.extension.logger.addLogMessage(`LaTeX fatal error: ${err.message}, ${stderr}. PID: ${pid}.`)
  this.extension.logger.addLogMessage(`Does the executable exist? PATH: ${process.env.PATH}`)
  - this.extension.logger.displayStatus('x', 'errorForeground', `Recipe terminated with fatal error: ${err.message}.`)
  + this.extension.logger.displayStatus('x', 'errorForeground', `Recipe terminated with fatal error: ${err.message}.`, 'error')
  this.currentProcess = undefined
  this.extension.buildInfo.buildEnded()
  releaseBuildMutex()
  