lsp: SignatureHelp.activeParameter can be -1

[notpeter]

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Describe the bug / provide steps to reproduce it

At least two LSPs (Dart and Eclipse jdtls) send SignatureHelp objects where the activeParameter is -1 which yields the following error:

[ERROR] failed to deserialize response from language server:
invalid value: integer `-1`, expected u32 at line 1 column 21.
response from language server: 
"{\"activeParameter\":-1,\"activeSignature\":0,\"signatures\"
...

In v3.16 of the LSP spec SignatureHelp.active_parameter is defined as uninteger.
In v3.15 it was merely specified as number.

This is out-of-spec (now), but Zed should handle this more gracefully.

Zed uses gluon-lang/lsp-types. lsp-types implements in signature_help.rs as u32:

pub struct SignatureHelp {
    pub signatures: Vec<SignatureInformation>,
    pub active_signature: Option<u32>,
    pub active_parameter: Option<u32>,
}

Upstream issues:

• Do not use u64 for numbers that could be negative gluon-lang/lsp-types#84
• signatureHelp returns activeParameter = -1 eclipse-jdtls/eclipse.jdt.ls#2434
• analysis server: SignatureHelp.activeParameter == -1 violates LSP spec dart-lang/sdk#58577

Originally discovered here:

• project restore/reopen starting multiple instance of language server  #20767 (comment)

Environment

Zed: v0.163.0 (Zed Nightly a35b73e)
OS: macOS 14.7.0
Memory: 64 GiB
Architecture: aarch64

If applicable, add mockups / screenshots to help explain present your vision of the feature

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If applicable, attach your Zed.log file to this issue.

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