ALE-like underscore/wavy for diagnostics

[Huxpro]

Is your feature request related to a problem? Please describe.

Currently, if ALE is not running along with this extension. The diagnostics from LSP only display sign in column and virtual texts but ignore the Range.

Describe the solution you'd like

Have native supports on that.
Btw, it seems like ALE itself is intended to evolve into a full-fledged language clients as well.
Do we want to depend on it?

Alternative

As CoC.vim? Show diagnostics via ALE.

Additional context

I am confusing by the fact that Updates - Diagnostics does show the underline. Does it come from ALE or this extension?

[autozimu]

There is no intention for this plugin to depend on other plugins regarding LSP as it is positioned to be the lowest level to talk to language servers.

The underline of GIF showing in Updates is indeed displayed by this plugin.

The styles for highlighting ranges of text are defined as

LanguageClient-neovim/doc/LanguageClient.txt

Lines 95 to 125 in 5491a64

	Default: >
	{
	1: {
	"name": "Error",
	"texthl": "ALEError",
	"signText": "✖",
	"signTexthl": "ALEErrorSign",
	"virtualTexthl": "Error",
	},
	2: {
	"name": "Warning",
	"texthl": "ALEWarning",
	"signText": "⚠",
	"signTexthl": "ALEWarningSign",
	"virtualTexthl": "Todo",
	},
	3: {
	"name": "Information",
	"texthl": "ALEInfo",
	"signText": "ℹ",
	"signTexthl": "ALEInfoSign",
	"virtualTexthl": "Todo",
	},
	4: {
	"name": "Hint",
	"texthl": "ALEInfo",
	"signText": "➤",
	"signTexthl": "ALEInfoSign",
	"virtualTexthl": "Todo",
	},
	}

. More specifically, it is texthl. You might want to make sure your theme display those highlight groups prominently or customize this setting to different highlight groups.