fix(loaders): trim whitespace around comma and at start/end of "scope".

Closes #1199.
Apparently this is supported by vscode, and its' no biggie, so let's
just do it too.

lua/luasnip/loaders/from_vscode.lua

@@ -102,7 +102,7 @@ local function get_file_snippets(file)
 
 		-- vscode documents `,`, but `.` also works.
 		-- an entry `false` in this list will cause a `ft=nil` for the snippet.
-		local filetypes = parts.scope and vim.split(parts.scope, "[.,]")
+		local filetypes = parts.scope and util.scopestring_to_filetypes(parts.scope)
 			or { false }
 
 		local contexts = {}

lua/luasnip/loaders/util.lua

@@ -281,6 +281,11 @@ local function normalize_opts(opts)
 	}
 end
 
+local function scopestring_to_filetypes(str)
+	local str_trimmed = str:gsub("^%s+", ""):gsub("%s+$", "")
+	return vim.split(str_trimmed, "%s*[.,]%s*")
+end
+
 return {
 	filetypelist_to_set = filetypelist_to_set,
 	split_lines = split_lines,
@@ -296,4 +301,5 @@ return {
 	get_load_fts = get_load_fts,
 	add_file_snippets = add_file_snippets,
 	normalize_opts = normalize_opts,
+	scopestring_to_filetypes = scopestring_to_filetypes
 }

tests/unit/loader_spec.lua

@@ -0,0 +1,17 @@
+local ls_helpers = require("helpers")
+local exec_lua, _, exec =
+	ls_helpers.exec_lua, ls_helpers.feed, ls_helpers.exec
+
+describe("luasnip.loaders.util:", function()
+	ls_helpers.clear()
+	exec("set rtp+=" .. os.getenv("LUASNIP_SOURCE"))
+
+	it("Correctly splits scopes with spaces.", function()
+		local res = exec_lua[[return require("luasnip.loaders.util").scopestring_to_filetypes("javascript, typescript")]]
+		assert.are.same({"javascript", "typescript"}, res)
+		local res = exec_lua[[return require("luasnip.loaders.util").scopestring_to_filetypes(" javascript, typescript")]]
+		assert.are.same({"javascript", "typescript"}, res)
+		local res = exec_lua[[return require("luasnip.loaders.util").scopestring_to_filetypes("javascript , typescript ")]]
+		assert.are.same({"javascript", "typescript"}, res)
+	end)
+end)