fix(core): only fail startup on actual errors (#202)

The latest version of OpenCode (1.1.35) outputs a log line to stderr on
startup (see anomalyco/opencode#10506 ). This
causes the NeoVim plugin to hang indefinitely.

This commit makes two changes:
1. If we fail to start the OpenCode server, we display a notification
   with the error rather than hanging indefinitely.
2. We don't allow DEBUG, INFO, or WARN-level messages to fail
   initialization.

Author: guill

lua/opencode/core.lua

@@ -85,7 +85,17 @@ M.open = Promise.async(function(opts)
     ui.focus_output({ restore_position = are_windows_closed })
   end
 
-  local server = server_job.ensure_server():await()
+  local server
+  local server_ok, server_err = pcall(function()
+    server = server_job.ensure_server():await()
+  end)
+
+  if not server_ok or not server then
+    state.is_opening = false
+    vim.notify('Failed to start opencode server: ' .. tostring(server_err or 'Unknown error'), vim.log.levels.ERROR)
+    return Promise.new():reject(server_err or 'Server failed to start')
+  end
+
   state.opencode_server = server
 
   local ok, err = pcall(function()

lua/opencode/opencode_server.lua

@@ -100,9 +100,21 @@ function OpencodeServer:spawn(opts)
       end
     end,
     stderr = function(err, data)
-      if err or data then
-        self.spawn_promise:reject(err or data)
-        safe_call(opts.on_error, err or data)
+      if err then
+        self.spawn_promise:reject(err)
+        safe_call(opts.on_error, err)
+        return
+      end
+      if data then
+        -- Filter out INFO/WARN/DEBUG log lines (not actual errors)
+        local log_level = data:match('^%s*(%u+)%s')
+        if log_level and (log_level == 'INFO' or log_level == 'WARN' or log_level == 'DEBUG') then
+          -- Ignore log lines, don't reject
+          return
+        end
+        -- Only reject on actual errors
+        self.spawn_promise:reject(data)
+        safe_call(opts.on_error, data)
       end
     end,
   }, function(exit_opts)