User now sees an error message when trying to paste an exercise with passed deadline

Author: matike

src/main/java/fi/helsinki/cs/tmc/cli/command/PasteCommand.java

@@ -91,6 +91,11 @@ public void run(CommandLine args, Io io) {
         CourseInfo courseinfo = CourseInfoIo.load(ctx.getWorkDir().getConfigFile());
         Exercise exercise = courseinfo.getExercise(exerciseName);
         URI uri = TmcUtil.sendPaste(ctx, exercise, message);
+        if (uri == null && exercise.hasDeadlinePassed()) {
+            io.println("Unable to send the paste."
+                    + " The deadline for submitting this exercise has passed");
+            return;
+        }
         if (uri == null) {
             io.println("Unable to send the paste");
             return;