message: Fixes Regression issue of vscode-languageclient since v3.0.0
diff: @@ -261,7 +261,7 @@ export function createConverter(uriConverter?: URIConverter): Converter {
  function asDiagnostic(item: code.Diagnostic): proto.Diagnostic {
  let result: proto.Diagnostic = proto.Diagnostic.create(asRange(item.range), item.message);
  - if (item.severity) { result.severity = asDiagnosticSeverity(item.severity); }
  + if (Is.number(item.severity)) { result.severity = asDiagnosticSeverity(item.severity); }
  if (Is.number(item.code) || Is.string(item.code)) { result.code = item.code; }
  if (item.source) { result.source = item.source; }
  return result;
  