Exit with special code upon unexpected error

ruby/lib/minitest/queue.rb

@@ -266,6 +266,11 @@ def run_from_queue(reporter, *)
       reopen_previous_step
       puts red("The heartbeat process died. This worker is exiting early.")
       exit!(41)
+    rescue => error
+      reopen_previous_step
+      puts red("This worker exited because of an uncaught application error:")
+      puts red("#{error.class}: #{error.message}")
+      exit!(42)
     end
   end
 end

ruby/test/fixtures/test/bad_framework_test.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+require "test_helper"
+
+class Minitest::Queue::SingleExample
+  def run
+    raise StandardError, "Some error in the test framework"
+  end
+end
+
+class BadFrameworkTest < Minitest::Test
+  def test_foo
+    assert false
+  end
+end

ruby/test/integration/minitest_redis_test.rb

@@ -933,6 +933,27 @@ def test_utf8_tests_and_marshal
       END
     end
 
+    def test_application_error
+      capture_subprocess_io do
+        system(
+          { 'BUILDKITE' => '1' },
+          @exe, 'run',
+          '--queue', @redis_url,
+          '--seed', 'foobar',
+          '--build', '1',
+          '--worker', '1',
+          '--timeout', '1',
+          '--max-requeues', '1',
+          '--requeue-tolerance', '1',
+          '-Itest',
+          'test/bad_framework_test.rb',
+          chdir: 'test/fixtures/',
+        )
+      end
+
+      assert_equal 42, $?.exitstatus
+    end
+
     private
 
     def normalize_xml(output)