Error executing lua callback: bad argument (nvim-cmp)

[tunaeskanaytac]

Hello everyone,
I've been trying to configure nvim-cmp for a while now. When I select a snippet provided by the lsp server, the snippet doesn't expand and I get the error message below.

The snippets provided by luasnip works fine.

When I searched the issue online, I could only find fixes changing window settings. But those didn't work for me either.

My cmp config is on the bottom of the post.

Thanks in advance.

Error executing vim.schedule lua callback: ...ck/myNeovimPackages/start/nvim-cmp/lua/cmp/utils/str.lua:81: bad argument #1 to 'byte' (string expected, got table)
stack traceback:
        [C]: in function 'byte'
        ...ck/myNeovimPackages/start/nvim-cmp/lua/cmp/utils/str.lua:81: in function 'trim'
        ...r/pack/myNeovimPackages/start/nvim-cmp/lua/cmp/entry.lua:457: in function 'get_documentation'
        ...NeovimPackages/start/nvim-cmp/lua/cmp/view/docs_view.lua:48: in function 'open'
        ...ir/pack/myNeovimPackages/start/nvim-cmp/lua/cmp/view.lua:299: in function 'callback'
        .../myNeovimPackages/start/nvim-cmp/lua/cmp/utils/async.lua:138: in function ''
        vim/_editor.lua: in function <vim/_editor.lua:0>
Press ENTER or type command to continue

    cmp-buffer.enable = true;
    cmp-nvim-lsp.enable = true;
    #cmp-nvim-lsp-signature-help.enable = true;
    cmp-path.enable = true;
    cmp_luasnip.enable = true;
    cmp-cmdline.enable = true;
    #cmp-cmdline-history.enable = true;
    #cmp-treesitter.enable = true;
    cmp = {
      enable = true;
      autoEnableSources = false;
      settings = {
        window = {
          completion = {
            border = "rounded";
            winhighlight = "Normal:Normal,FloatBorder:FloatBorder,CursorLine:Visual,Search:None";
          };
          documentation = {
            border = "rounded";
          };
        };
        formatting = {
          fields = ["kind" "abbr" "menu"];
          expandable_indicator = true;
        };

        sources = [
          {name = "nvim_lsp";}
          {name = "luasnip";}
          {name = "buffer";}
          {name = "path";}
          {name = "cmdline";}
          #{name = "nvim_lsp_signature_help";}
          #{name = "treesitter";}
        ];

        mapping = {
          "<C-Space>" = "cmp.mapping.complete()";
          "<C-d>" = "cmp.mapping.scroll_docs(-4)";
          "<C-e>" = "cmp.mapping.close()";
          "<C-f>" = "cmp.mapping.scroll_docs(4)";
          "<CR>" = "cmp.mapping.confirm({ select = true })";
          "<S-Tab>" = "cmp.mapping(cmp.mapping.select_prev_item(), {'i', 's'})";
          "<Tab>" = "cmp.mapping(cmp.mapping.select_next_item(), {'i', 's'})";
        };

        snippet = {
          expand = ''
            function(args)
              require('luasnip').lsp_expand(args.body)
            end
          '';
        };

        formatting.format = ''
          function(entry, vim_item)
            local kind_icons = {
              Text = "󰊄",
              Method = "",
              Function = "󰡱",
              Constructor = "",
              Field = "",
              Variable = "󱀍",
              Class = "",
              Interface = "",
              Module = "󰕳",
              Property = "",
              Unit = "",
              Value = "",
              Enum = "",
              Keyword = "",
              Snippet = "",
              Color = "",
              File = "",
              Reference = "",
              Folder = "",
              EnumMember = "",
              Constant = "",
              Struct = "",
              Event = "",
              Operator = "",
              TypeParameter = "",
            }
            vim_item.kind = string.format("%s", kind_icons[vim_item.kind])
            vim_item.menu = ({
              path = "[Path]",
              nvim_lua = "[NVIM_LUA]",
              nvim_lsp = "[LSP]",
              luasnip = "[Snippet]",
              buffer = "[Buffer]",
              treesitter = "[TreeSitter]",
            })[entry.source.name]
            return vim_item
          end
        '';
      };
    };