style: fix linting errors

lua/null-ls/diagnostics.lua

@@ -44,21 +44,20 @@ end
 
 -- assume 1-indexed ranges
 local convert_range = function(diagnostic)
-    local row = tonumber(diagnostic.row or 1)
-    local col = tonumber(diagnostic.col or 1)
-    local end_row = tonumber(diagnostic.end_row or row)
-    local end_col = tonumber(diagnostic.end_col or 1)
+    local format = function(...)
+        return ("cannot convert %s to number"):format(...)
+    end
+
+    local row = assert(tonumber(diagnostic.row or 1), format(diagnostic.row))
+    local col = assert(tonumber(diagnostic.col or 1), format(diagnostic.col))
+    local end_row = assert(tonumber(diagnostic.end_row or row), format(diagnostic.end_row or row))
+    local end_col = assert(tonumber(diagnostic.end_col or 1), format(diagnostic.end_col))
     -- wrap to next line
     if end_row == row and end_col <= col then
         end_row = end_row + 1
         end_col = 1
     end
 
-    assert(row)
-    assert(col)
-    assert(end_row)
-    assert(end_col)
-
     return u.range.to_lsp({ row = row, col = col, end_row = end_row, end_col = end_col })
 end
 

lua/null-ls/helpers/range_formatting_args_factory.lua

@@ -29,8 +29,7 @@ local range_formatting_args_factory = function(base_args, start_arg, end_arg, op
             return args
         end
 
-        local range = params.range
-        assert(range)
+        local range = assert(params.range, "params.range is nil")
         local row, col, end_row, end_col = range.row, range.col, range.end_row, range.end_col
         if opts.row_offset then
             row = row + opts.row_offset

lua/null-ls/loop.lua

@@ -271,10 +271,18 @@ end
 M.read_file = function(path)
     local content
     local ok, err = pcall(function()
-        local fd = uv.fs_open(path, "r", 438)
-        assert(fd)
-        local stat = uv.fs_fstat(fd)
-        assert(stat)
+        local err_name, err_msg
+        local fd
+        local stat
+
+        local fmt = function(...)
+            return ("[Error %s]: %s"):format(...)
+        end
+
+        fd, err_name, err_msg = uv.fs_open(path, "r", 438)
+        assert(fd, fmt(err_name, err_msg))
+        stat, err_name, err_msg = uv.fs_fstat(fd)
+        assert(stat, fmt(err_name, err_msg))
         content = uv.fs_read(fd, stat.size, 0)
         uv.fs_close(fd)
     end)

lua/null-ls/utils/init.lua

@@ -120,8 +120,7 @@ M.make_conditional_utils = function()
             return false
         end,
         root_has_file_matches = function(pattern)
-            local handle = vim.uv.fs_scandir(root)
-            assert(handle)
+            local handle = assert(vim.uv.fs_scandir(root), "Unable to scan " .. root)
             local entry = vim.uv.fs_scandir_next(handle)
 
             while entry do
@@ -229,15 +228,14 @@ M.get_root = function()
     if not root then
         local fname = api.nvim_buf_get_name(0)
         if fname ~= "" then
-            local v = require("null-ls.config").get().root_dir(fname)
-            assert(v)
+            local v = assert(require("null-ls.config").get().root_dir(fname), "cannot infer root_dir")
             root = v
         end
     end
 
     -- fall back to cwd
-    local cwd = vim.uv.cwd()
-    assert(cwd)
+    local cwd, err_name, err_msg = vim.uv.cwd()
+    assert(cwd, string.format("[Error %s]: %s", err_name, err_msg))
 
     return root or cwd
 end
@@ -366,8 +364,8 @@ end
 ---@return string|nil
 M.get_vcs_root = function()
     local uv = vim.uv
-    local cwd = uv.cwd()
-    assert(cwd)
+    local cwd, err_name, err_msg = uv.cwd()
+    assert(cwd, string.format("[Error %s]: %s", err_name, err_msg))
     local vcs_root = M.root_pattern(".git", ".hg", ".svn", ".bzr")(cwd)
     return vcs_root
 end