message: refactor(localize): remove unnecessary ! operator
  The messages property always exists so there is no need for the ! operator.
  PR Close
diff: @@ -35,8 +35,8 @@ export class Diagnostics {
  this.messages.push(...other.messages);
  }
  formatDiagnostics(message: string): string {
  - const errors = this.messages!.filter(d => d.type === 'error').map(d => ' - ' + d.message);
  - const warnings = this.messages!.filter(d => d.type === 'warning').map(d => ' - ' + d.message);
  + const errors = this.messages.filter(d => d.type === 'error').map(d => ' - ' + d.message);
  + const warnings = this.messages.filter(d => d.type === 'warning').map(d => ' - ' + d.message);
  if (errors.length) {
  message += '\nERRORS:\n' + errors.join('\n');
  }
  