vscode java dependency plugin error when expand class node

[yeweiasia]

Description

vscode java dependency plugin throw errors when expand class node in
javaDependencyExplorer

Reproduction Steps

OS and Theia version:
ubuntu 18.04
theia 0.9.0
vscode java dependency viewer: 0.5.1

Diagnostics:

backend log:

root ERROR Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:470:11)
    at ServerResponse.header (/home/yewei/Workspace/theia/node_modules/express/lib/response.js:767:10)
    at ServerResponse.send (/home/yewei/Workspace/theia/node_modules/express/lib/response.js:170:12)
    at /home/yewei/Workspace/theia/packages/plugin-ext/lib/hosted/node/plugin-reader.js:112:37
    at /home/yewei/Workspace/theia/node_modules/express/lib/response.js:430:22
    at SendStream.onend (/home/yewei/Workspace/theia/node_modules/express/lib/response.js:1047:5)
    at SendStream.emit (events.js:189:13)
    at ReadStream.onend (/home/yewei/Workspace/theia/node_modules/send/index.js:822:10)
    at ReadStream.emit (events.js:194:15)
    at endReadableNT (_stream_readable.js:1125:12)
root ERROR Uncaught Exception:  Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
root ERROR Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:470:11)
    at ServerResponse.header (/home/yewei/Workspace/theia/node_modules/express/lib/response.js:767:10)
    at ServerResponse.send (/home/yewei/Workspace/theia/node_modules/express/lib/response.js:170:12)
    at /home/yewei/Workspace/theia/packages/plugin-ext/lib/hosted/node/plugin-reader.js:112:37
    at /home/yewei/Workspace/theia/node_modules/express/lib/response.js:430:22
    at SendStream.onend (/home/yewei/Workspace/theia/node_modules/express/lib/response.js:1047:5)
    at SendStream.emit (events.js:189:13)
    at ReadStream.onend (/home/yewei/Workspace/theia/node_modules/send/index.js:822:10)
    at ReadStream.emit (events.js:194:15)
    at endReadableNT (_stream_readable.js:1125:12)
root ERROR Failed to fetch children for 'javaDependencyExplorer' Error: The command 'vscode.executeDocumentSymbolProvider' cannot be executed. There are no active handlers available for the command. (args: [{"$mid":1,"path":"/home/yewei/Workspace/demo/src/main/java/com/example/demo/Apple.java","scheme":"file"}])
    at CommandRegistry. (http://192.168.31.211:3000/bundle.js:109511:31)
    at step (http://192.168.31.211:3000/bundle.js:109287:23)
    at Object.next (http://192.168.31.211:3000/bundle.js:109268:53)
    at fulfilled (http://192.168.31.211:3000/bundle.js:109259:58)
root ERROR Failed to fetch children for 'javaDependencyExplorer' Error: The command 'vscode.executeDocumentSymbolProvider' cannot be executed. There are no active handlers available for the command. (args: [{"$mid":1,"path":"/home/yewei/Workspace/demo/src/main/java/com/example/demo/Apple.java","scheme":"file"}])
    at CommandRegistry. (http://192.168.31.211:3000/bundle.js:109511:31)
    at step (http://192.168.31.211:3000/bundle.js:109287:23)
    at Object.next (http://192.168.31.211:3000/bundle.js:109268:53)
    at fulfilled (http://192.168.31.211:3000/bundle.js:109259:58)

web browser console log:

[akosyakov]

It's caused by #4048

[akosyakov]

@yeweiasia Could you check again please? The missing command was implemented already.

[yeweiasia]

@akosyakov
the errors seems to be fixed ,but the function of jumping to the position works a bit weird.