'julia/getModuleAt' sometimes fails with MethodError

[pfitzseb]

┌ Warning: Some Julia code in the VS Code extension crashed with
│   e =
│    MethodError: no method matching parentof(::Nothing)
│    Closest candidates are:
│      parentof(!Matched::StaticLint.Scope) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/StaticLint/src/scope.jl:92
│      parentof(!Matched::CSTParser.EXPR) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/CSTParser/src/spec.jl:294
└ @ Main ~/Documents/Git/julia-vscode/scripts/error_handler.jl:5
ERROR: MethodError: no method matching parentof(::Nothing)
Closest candidates are:
  parentof(!Matched::StaticLint.Scope) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/StaticLint/src/scope.jl:92
  parentof(!Matched::CSTParser.EXPR) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/CSTParser/src/spec.jl:294
Stacktrace:
 [1] retrieve_scope(::Nothing) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/StaticLint/src/utils.jl:138
 [2] process(::LanguageServer.JSONRPC.Request{Val{Symbol("julia/getModuleAt")},LanguageServer.TextDocumentPositionParams}, ::LanguageServerInstance) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/LanguageServer/src/requests/features.jl:314
 [3] run(::LanguageServerInstance) at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/packages/LanguageServer/src/languageserverinstance.jl:251
 [4] top-level scope at /home/pfitzseb/Documents/Git/julia-vscode/scripts/languageserver/main.jl:59
 [5] include(::Module, ::String) at ./Base.jl:377
 [6] exec_options(::Base.JLOptions) at ./client.jl:288
 [7] _start() at ./client.jl:484

Not 100% what triggers this though.

[pfitzseb]

Ok, so when the current position is in whitespace then get_expr1 returns nothing. The best solution here would be to call something like next_expr, but I'm not sure if we have that already. Could presumably just increment the offset until we find an expr?

[pfitzseb]

This also seems like it could just run in a try catch because we fall back to Main anyways.

[ZacLN]

There's a version of get_expr that always returns an EXPR, I'll have a look and work out which one. The getModule handler should also probably be adjusted to handle a nothing response as well though (to return Main?) - e.g. in the case of an empty document.

[pfitzseb]

Yea. Currently branching on nothing is really annoying because the module changes between whitespace and actual code.