Improved exception handling in service.

src/service.cr

@@ -377,5 +377,10 @@ begin
 rescue e : Service::Exception
 	context.error e.message
 	exit 2
+rescue e
+	STDERR.puts "unhandled exception: #{e.message}"
+	e.backtrace.map do |line|
+		STDERR << "  - " << line << '\n'
+	end
 end