fix(footnotes): add nil check in goto_definition navigation (#208)

Author: YousefHadder

lua/markdown-plus/footnotes/navigation.lua

@@ -29,6 +29,14 @@ function M.goto_definition()
 
   -- Jump to definition, position cursor after ": "
   local line = vim.api.nvim_buf_get_lines(bufnr, def.line_num - 1, def.line_num, false)[1]
+  if not line then
+    local line_count = vim.api.nvim_buf_line_count(bufnr)
+    local target_line = math.min(def.line_num, line_count)
+    vim.cmd("normal! m'")
+    vim.api.nvim_win_set_cursor(0, { target_line, 0 })
+    utils.notify("Footnote definition moved; jumped to nearest available line", vim.log.levels.INFO)
+    return
+  end
   local content_start = line:find(":%s*")
   if content_start then
     content_start = content_start + 1

spec/markdown-plus/footnotes_spec.lua

@@ -428,4 +428,56 @@ describe("markdown-plus footnotes", function()
       assert.equals(true, config.confirm_delete)
     end)
   end)
+
+  describe("navigation", function()
+    local navigation = require("markdown-plus.footnotes.navigation")
+
+    describe("goto_definition", function()
+      it("jumps to footnote definition from reference", function()
+        vim.api.nvim_buf_set_lines(0, 0, -1, false, {
+          "Text with[^1] footnote.",
+          "",
+          "[^1]: The definition.",
+        })
+        vim.api.nvim_win_set_cursor(0, { 1, 11 }) -- on [^1]
+
+        navigation.goto_definition()
+
+        local cursor = vim.api.nvim_win_get_cursor(0)
+        assert.equals(3, cursor[1])
+      end)
+
+      it("does not error when definition line is out of range", function()
+        vim.api.nvim_buf_set_lines(0, 0, -1, false, {
+          "Text with[^1] footnote.",
+          "",
+          "[^1]: The definition.",
+        })
+        vim.api.nvim_win_set_cursor(0, { 1, 11 }) -- on [^1]
+
+        -- Stub nvim_buf_get_lines to return empty (simulating buffer shrink)
+        local orig_get_lines = vim.api.nvim_buf_get_lines
+        vim.api.nvim_buf_get_lines = function(buf, start, stop, strict)
+          -- Only intercept the single-line read for the definition
+          if start == 2 and stop == 3 then
+            return {}
+          end
+          return orig_get_lines(buf, start, stop, strict)
+        end
+
+        local success = pcall(function()
+          navigation.goto_definition()
+        end)
+
+        vim.api.nvim_buf_get_lines = orig_get_lines
+        assert.is_true(success, "goto_definition should not error when line is nil")
+
+        -- Verify cursor jumped to a safe position (clamped to buffer line count)
+        local cursor = vim.api.nvim_win_get_cursor(0)
+        local line_count = vim.api.nvim_buf_line_count(0)
+        assert.is_true(cursor[1] >= 1 and cursor[1] <= line_count, "cursor should be within buffer bounds")
+        assert.equals(0, cursor[2], "cursor column should be 0 on fallback")
+      end)
+    end)
+  end)
 end)