Error on hover: lllegal argument, contents must be defined

v0.4.0

in VSCode, create a sample project and add the file

package com.aeschli.testapp;

public class TestHelper {
    public static boolean compare(String a, String b) {
        return a.compareToIgnoreCase(b) == 0;
    }
}

move the mouse over boolean
the dev tools console shows

    at new e (/usr/share/code-insiders/resources/app/out/vs/workbench/node/extensionHostProcess.js:4:227228)
    at asHover (/home/aeschli/.vscode-insiders/extensions/redhat.java-0.4.0/node_modules/vscode-languageclient/lib/protocolConverter.js:63:16)
e.onUnexpectedError @ workbench.main.js:29

The problem seems to be that the hover object sent across the line doesn't contain a 'contents' field.

You created the project before or after opening vscode?

I created it while it was open, but in the meantime also started VSCode again on the project.

I think it's a bug on the Java language server side. If a location doesn't have any hover to show, send 'null' as result, not a hover without contents.

Ok I can reproduce the issue.

I think we send a non null Hover because lsp4j would crap out otherwise, but I need to check

@aeschli

@aeschli it's actually VS Code that doesn't like null results:

[Error - 10:49:50 AM] Request textDocument/hover failed.
Error: The received response has neither a result nor an error property.
    at handleInvalidMessage (/Users/fbricon/Dev/projects/vscode-java/node_modules/vscode-jsonrpc/lib/main.js:381:40)
    at StreamMessageReader.callback (/Users/fbricon/Dev/projects/vscode-java/node_modules/vscode-jsonrpc/lib/main.js:492:13)
    at StreamMessageReader.onData (/Users/fbricon/Dev/projects/vscode-java/node_modules/vscode-jsonrpc/lib/messageReader.js:199:18)
    at Socket.<anonymous> (/Users/fbricon/Dev/projects/vscode-java/node_modules/vscode-jsonrpc/lib/messageReader.js:166:19)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:188:7)
    at readableAddChunk (_stream_readable.js:176:18)
    at Socket.Readable.push (_stream_readable.js:134:10)
    at Pipe.onread (net.js:551:20)

Yes, it can be discussed where the bug is. From how I understand the spec, 'contents' is a required field for hover.
That said, I created microsoft/vscode-languageserver-node#207 to be tolerant in the language client.

#214 (comment)
I guess you didn't pass in a result at all. The code there checks for undefined. I think it should be at least 'null'.

Yes it was when I sent a null Hover result instead of an Hover result with null content (your initial report)

Don't send hover with null content

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Error on hover: lllegal argument, contents must be defined #214

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Error on hover: lllegal argument, contents must be defined #214

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fbricon commented on May 16, 2017

aeschli commented on May 16, 2017

aeschli commented on May 16, 2017

fbricon commented on May 16, 2017

fbricon commented on May 16, 2017

aeschli commented on May 16, 2017

aeschli commented on May 16, 2017

fbricon commented on May 16, 2017

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