fix(ollama): properly handle errors from curl when querying models

Without on_error() handler curl.get() will raise an error which then
will interrupt execution of the plenary job. This interruption will
result in timeout handling code triggering, introducing unneeded delay
and ugly stack traces.

Fix the problem by defining on_error() and callback() handlers and
explicitly wait for job completion with pcall() and Job:wait(). This
allows proper error handling and control over error messages.

Because plenary's curl implementation mangles stderr data, use a local
table to map select error codes to descriptive text messages.

Also do not emit hard error when endpoint is not configured, use
Utils.error().

lua/avante/providers/ollama.lua

@@ -247,6 +247,21 @@ M.on_error = function(result)
   Utils.error(error_msg, { title = "Ollama" })
 end
 
+local curl_errors = {
+  [1] = "Unsupported protocol",
+  [3] = "URL malformed",
+  [5] = "Could not resolve proxy",
+  [6] = "Could not resolve host",
+  [7] = "Failed to connect to host",
+  [23] = "Failed writing received data to disk",
+  [28] = "Operation timed out",
+  [35] = "SSL/TLS connection error",
+  [47] = "Too many redirects",
+  [52] = "Server returned empty response",
+  [56] = "Failure in receiving network data",
+  [60] = "Peer certificate cannot be authenticated with known CA certificates (SSL cert issue)",
+}
+
 -- List available models using Ollama's tags API
 function M:list_models()
   -- Return cached models if available
@@ -254,7 +269,10 @@ function M:list_models()
 
   -- Parse provider config and construct tags endpoint URL
   local provider_conf = Providers.parse_config(self)
-  if not provider_conf.endpoint then error("Ollama requires endpoint configuration") end
+  if not provider_conf.endpoint then
+    Utils.error("Ollama requires endpoint configuration")
+    return {}
+  end
 
   local curl = require("plenary.curl")
   local tags_url = Utils.url_join(provider_conf.endpoint, "/api/tags")
@@ -265,8 +283,21 @@ function M:list_models()
   local headers = Utils.tbl_override(base_headers, self.extra_headers)
 
   -- Request the model tags from Ollama
-  local response = curl.get(tags_url, { headers = headers })
-  if response.status ~= 200 then
+  local response = {}
+  local job = curl.get(tags_url, {
+    headers = headers,
+    callback = function(output) response = output end,
+    on_error = function(err) response = { exit = err.exit } end,
+  })
+  local job_ok, error = pcall(job.wait, job, 10000)
+  if not job_ok then
+    Utils.error("Ollama: curl command invocation failed: " .. error)
+    return {}
+  elseif response.exit ~= 0 then
+    local err_msg = curl_errors[response.exit] or ("curl returned error: " .. response.exit)
+    Utils.error("Ollama: " .. err_msg)
+    return {}
+  elseif response.status ~= 200 then
     Utils.error("Failed to fetch Ollama models: " .. (response.body or response.status))
     return {}
   end