cleanup diagnostics in DiagnosticRequestor (#976)
cleanup diagnostics in DiagnosticRequestor (#976)

try to fix #975

Co-authored-by: Dirk Bäumer <5807b9c49537230a1b3fe16b43f1e9b46364072a@microsoft.com>
microsoft/vscode-languageserver-node,microsoft/vscode-languageserver-node,microsoft/vscode-languageserver-node,microsoft/vscode-languageserver-node