fix: mistyped handlers

Author: tjdevries

lua/completion/signature_help.lua

@@ -30,7 +30,7 @@ M.autoOpenSignatureHelp = function()
     local params = vim.lsp.util.make_position_params()
     vim.lsp.buf_request(0, 'textDocument/signatureHelp', params, function(err, method, result, client_id)
       local client = vim.lsp.get_client_by_id(client_id)
-      local handler = client and client.handler['textDocument/signatureHelp']
+      local handler = client and client.handlers['textDocument/signatureHelp']
       if handler then
           handler(err, method, result, client_id)
           return