#8343 return 400 on broken url

Fixes #8471

logstash-core/lib/logstash/api/modules/node.rb

@@ -11,13 +11,19 @@ module LogStash
         end
 
         get "/hot_threads" do
+          begin
             ignore_idle_threads = params["ignore_idle_threads"] || true
 
-          options = { :ignore_idle_threads => as_boolean(ignore_idle_threads) }
+            options = {:ignore_idle_threads => as_boolean(ignore_idle_threads)}
             options[:threads] = params["threads"].to_i if params.has_key?("threads")
 
             as = human? ? :string : :json
             respond_with(node.hot_threads(options), {:as => as})
+          rescue ArgumentError => e
+            response = respond_with({"error" => e.message})
+            status(400)
+            response
+          end
         end
 
         get "/pipelines/:id" do

logstash-core/lib/logstash/api/modules/stats.rb

@@ -9,6 +9,7 @@ module LogStash
 
         # return hot threads information
         get "/jvm/hot_threads" do
+          begin
             top_threads_count = params["threads"] || 3
             ignore_idle_threads = params["ignore_idle_threads"] || true
             options = {
@@ -17,6 +18,11 @@ module LogStash
             }
 
             respond_with(stats_command.hot_threads(options))
+          rescue ArgumentError => e
+            response = respond_with({"error" => e.message})
+            status(400)
+            response
+          end
         end
 
         # return hot threads information

logstash-core/spec/logstash/api/modules/node_spec.rb

@@ -46,6 +46,17 @@ describe LogStash::Api::Modules::Node do
       end
     end
 
+    context "broken params in URL" do
+
+      before(:all) do
+        get "/hot_threads?human=?threads=5"
+      end
+
+      it "should return http status 400" do
+        expect(last_response.status).to eq(400)
+      end
+    end
+
     context "when asking for human output" do
       [
         "/hot_threads?human",