fix: more robust icon provider resolution

## Details

Issue: #403

The `get` call into `mini.icons` can sometimes be `nil`, while I'm
unable to replicate it we can definitely make this module more robust
by adding more checks than a `pcall` around `require`.

To fix this the logic has been entirely re-written. In addition to
`pcall` we now also:

- validate the required module is not `nil`
- validate that the method we use for the provider is not `nil`
- validate `_G.MiniIcons ~= nil` as specified in the docs

Minor other changes:

- pull `default` configuration directly in state module where needed
- add an `alias` for `dash` width type
- consistently call cache tables  `Cache` and use `class` annotation
- `render.md.BufferConfig` -> `render.md.main.Config`
- directly invalidate state cache in `init` module

Author: MeanderingProgrammer

doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*           For 0.11.0          Last change: 2025 April 17
+*render-markdown.txt*           For 0.11.0          Last change: 2025 April 21
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*

lua/render-markdown/api.lua

@@ -54,8 +54,7 @@ function M.debug()
 end
 
 function M.config()
-    local markdown = require('render-markdown')
-    local difference = state.difference(markdown.default)
+    local difference = state.difference()
     if vim.tbl_count(difference) == 0 then
         vim.print('Default Configuration')
     else

lua/render-markdown/colors.lua

@@ -1,4 +1,4 @@
----@class render.md.cache.Colors
+---@class render.md.colors.Cache
 ---@field combine table<string, { fg: string, bg: string }>
 ---@field bg_to_fg table<string, { hl: string }>
 local Cache = {

lua/render-markdown/config.lua

@@ -1,18 +1,18 @@
 local Env = require('render-markdown.lib.env')
 local Range = require('render-markdown.core.range')
 
----@class render.md.Components
+---@class render.md.main.Components
 ---@field callout table<string, render.md.callout.Config>
 ---@field checkbox table<string, render.md.checkbox.custom.Config>
 
----@class render.md.BufferConfig: render.md.buffer.Config
+---@class render.md.main.Config: render.md.buffer.Config
 ---@field private modes render.md.Modes
----@field private components render.md.Components
+---@field private components render.md.main.Components
 local Config = {}
 Config.__index = Config
 
 ---@param config render.md.buffer.Config
----@return render.md.BufferConfig
+---@return render.md.main.Config
 function Config.new(config)
     -- Super set of render modes across top level and individual components
     local modes = config.render_modes
@@ -22,7 +22,7 @@ function Config.new(config)
         end
     end
 
-    ---@type render.md.Components
+    ---@type render.md.main.Components
     local components = {
         callout = Config.normalize(config.callout),
         checkbox = Config.normalize(config.checkbox.custom),
@@ -119,19 +119,17 @@ end
 ---@param row? integer
 ---@return render.md.Range?
 function Config:hidden(mode, row)
-    -- Anti-conceal is not enabled -> hide nothing
-    -- Row is not known -> buffer is not active -> hide nothing
-    if not self.anti_conceal.enabled or row == nil then
+    -- anti-conceal is not enabled -> hide nothing
+    -- row is not known -> buffer is not active -> hide nothing
+    local config = self.anti_conceal
+    if not config.enabled or row == nil then
         return nil
     end
     if vim.tbl_contains({ 'v', 'V', '\22' }, mode) then
         local start = vim.fn.getpos('v')[2] - 1
         return Range.new(math.min(row, start), math.max(row, start))
     else
-        return Range.new(
-            row - self.anti_conceal.above,
-            row + self.anti_conceal.below
-        )
+        return Range.new(row - config.above, row + config.below)
     end
 end
 

lua/render-markdown/config/dash.lua

@@ -1,9 +1,11 @@
 ---@class (exact) render.md.dash.Config: render.md.base.Config
 ---@field icon string
----@field width 'full'|number
+---@field width render.md.dash.Width
 ---@field left_margin number
 ---@field highlight string
 
+---@alias render.md.dash.Width 'full'|number
+
 local M = {}
 
 ---@param spec render.md.debug.ValidatorSpec

lua/render-markdown/core/context.lua

@@ -220,29 +220,29 @@ function Context:for_each(callback)
     return false
 end
 
----@type table<integer, render.md.Context>
-local cache = {}
+---@class render.md.context.Cache: { [integer]: render.md.Context }
+local Cache = {}
 
----@class render.md.ContextManager
+---@class render.md.context.Manager
 local M = {}
 
 ---@param props render.md.context.Props
 function M.reset(props)
-    cache[props.buf] = Context.new(props, 10)
+    Cache[props.buf] = Context.new(props, 10)
 end
 
 ---@param buf integer
 ---@param win integer
 ---@return boolean
 function M.contains_range(buf, win)
-    local context = cache[buf]
+    local context = Cache[buf]
     return context ~= nil and context:contains_window(win)
 end
 
 ---@param buf integer
 ---@return render.md.Context
 function M.get(buf)
-    return cache[buf]
+    return Cache[buf]
 end
 
 return M

lua/render-markdown/core/log.lua

@@ -12,6 +12,7 @@ local Env = require('render-markdown.lib.env')
 ---@field private file string
 local M = {}
 
+---Should only be called from state on setup
 ---@param level render.md.config.LogLevel
 function M.setup(level)
     -- Write out any logs before closing

lua/render-markdown/core/ui.lua

@@ -23,7 +23,7 @@ local builtin_handlers = {
     markdown_inline = require('render-markdown.handler.markdown_inline'),
 }
 
----@class render.md.cache.Ui
+---@class render.md.ui.Cache
 ---@field states table<integer, render.md.Buffer>
 local Cache = {
     states = {},
@@ -97,7 +97,8 @@ function M.update(buf, win, event, change)
     end
 
     local parse = M.parse(buf, win, change)
-    local config, buffer = state.get(buf), Cache.get(buf)
+    local config = state.get(buf)
+    local buffer = Cache.get(buf)
     if buffer:is_empty() then
         return
     end
@@ -181,7 +182,7 @@ function M.run_update(buf, win, change)
 end
 
 ---@private
----@param config render.md.BufferConfig
+---@param config render.md.main.Config
 ---@param win integer
 ---@param mode string
 ---@return 'default'|'rendered'

lua/render-markdown/handler/html.lua

@@ -4,7 +4,7 @@ local state = require('render-markdown.state')
 local ts = require('render-markdown.integ.ts')
 
 ---@class render.md.handler.buf.Html
----@field private config render.md.BufferConfig
+---@field private config render.md.main.Config
 ---@field private context render.md.Context
 ---@field private marks render.md.Marks
 ---@field private query vim.treesitter.Query

lua/render-markdown/handler/latex.lua

@@ -6,8 +6,8 @@ local Str = require('render-markdown.lib.str')
 local log = require('render-markdown.core.log')
 local state = require('render-markdown.state')
 
----@type table<string, string>
-local cache = {}
+---@class render.md.latex.Cache: { [string]: string }
+local Cache = {}
 
 ---@class render.md.handler.Latex: render.md.Handler
 local M = {}
@@ -27,14 +27,14 @@ function M.parse(ctx)
     local node = Node.new(ctx.buf, ctx.root)
     log.node('latex', node)
 
-    local raw_expression = cache[node.text]
+    local raw_expression = Cache[node.text]
     if raw_expression == nil then
         raw_expression = vim.fn.system(latex.converter, node.text)
         if vim.v.shell_error == 1 then
             log.add('error', latex.converter, raw_expression)
             raw_expression = 'error'
         end
-        cache[node.text] = raw_expression
+        Cache[node.text] = raw_expression
     end
 
     local expressions = {} ---@type string[]

lua/render-markdown/handler/markdown.lua

@@ -4,7 +4,7 @@ local state = require('render-markdown.state')
 local ts = require('render-markdown.integ.ts')
 
 ---@class render.md.handler.buf.Markdown
----@field private config render.md.BufferConfig
+---@field private config render.md.main.Config
 ---@field private context render.md.Context
 ---@field private marks render.md.Marks
 ---@field private query vim.treesitter.Query

lua/render-markdown/handler/markdown_inline.lua

@@ -4,7 +4,7 @@ local state = require('render-markdown.state')
 local ts = require('render-markdown.integ.ts')
 
 ---@class render.md.handler.buf.MarkdownInline
----@field private config render.md.BufferConfig
+---@field private config render.md.main.Config
 ---@field private context render.md.Context
 ---@field private marks render.md.Marks
 ---@field private query vim.treesitter.Query

lua/render-markdown/health.lua

@@ -1,11 +1,11 @@
-local Icons = require('render-markdown.lib.icons')
+local Icons = require('render-markdown.integ.icons')
 local state = require('render-markdown.state')
 
 ---@class render.md.Health
 local M = {}
 
 ---@private
-M.version = '8.3.1'
+M.version = '8.3.2'
 
 function M.check()
     M.start('version')
@@ -33,7 +33,7 @@ function M.check()
     M.check_highlight('markdown')
 
     M.start('icons')
-    local provider = Icons.provider()
+    local provider = Icons.name()
     if provider ~= nil then
         vim.health.ok('using: ' .. provider)
     else
@@ -65,17 +65,15 @@ function M.start(name)
 end
 
 ---@private
----@param minimum string
----@param recommended string
-function M.neovim(minimum, recommended)
-    if vim.fn.has('nvim-' .. minimum) == 0 then
-        vim.health.error('neovim < ' .. minimum)
-    elseif vim.fn.has('nvim-' .. recommended) == 0 then
-        vim.health.warn(
-            'neovim < ' .. recommended .. ' some features will not work'
-        )
+---@param min string
+---@param rec string
+function M.neovim(min, rec)
+    if vim.fn.has('nvim-' .. min) == 0 then
+        vim.health.error('neovim < ' .. min)
+    elseif vim.fn.has('nvim-' .. rec) == 0 then
+        vim.health.warn('neovim < ' .. rec .. ' some features will not work')
     else
-        vim.health.ok('neovim >= ' .. recommended)
+        vim.health.ok('neovim >= ' .. rec)
     end
 end
 

lua/render-markdown/init.lua

@@ -714,7 +714,8 @@ function M.setup(opts)
     end
     M.initialized = true
 
-    require('render-markdown.state').setup(M.default, opts or {})
+    require('render-markdown.state').setup(opts or {})
+    require('render-markdown.state').invalidate_cache()
     require('render-markdown.core.ui').invalidate_cache()
 end
 

lua/render-markdown/integ/icons.lua

@@ -0,0 +1,91 @@
+---@class render.md.icon.Provider
+---@field name? string
+---@field get fun(filetype: string): string?, string?
+
+---@class render.md.icon.Providers
+Providers = {}
+
+---@return render.md.icon.Provider?
+function Providers.MiniIcons()
+    local has, icons = pcall(require, 'mini.icons')
+    if not has or icons == nil then
+        return nil
+    end
+    local getter = icons.get
+    if getter == nil then
+        return nil
+    end
+    -- additional check recommended by author
+    if _G.MiniIcons == nil then
+        return nil
+    end
+    ---@type render.md.icon.Provider
+    return {
+        name = 'mini.icons',
+        get = function(filetype)
+            return getter('filetype', filetype)
+        end,
+    }
+end
+
+---@return render.md.icon.Provider?
+function Providers.DevIcons()
+    local has, icons = pcall(require, 'nvim-web-devicons')
+    if not has or icons == nil then
+        return nil
+    end
+    local getter = icons.get_icon_by_filetype
+    if getter == nil then
+        return nil
+    end
+    ---@type render.md.icon.Provider
+    return {
+        name = 'nvim-web-devicons',
+        get = function(filetype)
+            return getter(filetype)
+        end,
+    }
+end
+
+---@return render.md.icon.Provider
+function Providers.None()
+    ---@type render.md.icon.Provider
+    return {
+        name = nil,
+        get = function()
+            return nil, nil
+        end,
+    }
+end
+
+---@class render.md.integ.Icons
+---@field private provider? render.md.icon.Provider
+local M = {}
+
+---@return string?
+function M.name()
+    return M.resolve().name
+end
+
+---@param name string
+---@return string?, string?
+function M.get(name)
+    -- handle input possibly being an extension rather than a language name
+    local filetype = vim.filetype.match({ filename = 'a.' .. name }) or name
+    return M.resolve().get(filetype)
+end
+
+---@private
+---@return render.md.icon.Provider
+function M.resolve()
+    local provider = M.provider
+    if provider == nil then
+        provider = provider or Providers.MiniIcons()
+        provider = provider or Providers.DevIcons()
+        provider = provider or Providers.None()
+        M.provider = provider
+    end
+    return provider
+end
+
+return M

lua/render-markdown/integ/source.lua

@@ -106,14 +106,13 @@ end
 ---@return boolean
 function M.ignore(marker, text)
     local prefix = vim.pesc(vim.trim(marker)) .. '%s+'
-    local patterns = {
-        -- The first non-space after the marker is not '['
-        prefix .. '[^%[]',
-        -- After '[' there is another '[' or a space
-        prefix .. '%[.*[%[%s]',
-        -- There is already text enclosed by '[' ']'
-        prefix .. '%[.*%]',
-    }
+    local patterns = {} ---@type string[]
+    -- first non-space after the marker is not '['
+    patterns[#patterns + 1] = prefix .. '[^%[]'
+    -- after '[' there is another '[' or a space
+    patterns[#patterns + 1] = prefix .. '%[.*[%[%s]'
+    -- there is already text enclosed by '[' ']'
+    patterns[#patterns + 1] = prefix .. '%[.*%]'
     for _, pattern in ipairs(patterns) do
         if text:find(pattern) ~= nil then
             return true