On error there is no need to pop the scope.

The error routines for task and function definitions were incorrectly
popping the scope. This should not be done since no scope was pushed.
Also assert that the current_task/function is 0 to catch that kind of
error like the other definition rules.

parse.y

@@ -2377,8 +2377,7 @@ module_item
 
   | K_task automatic_opt IDENTIFIER error K_endtask
       {
-	pform_pop_scope();
-	current_task = 0;
+	assert(current_task == 0);
 	delete[]$3;
       }
 
@@ -2418,8 +2417,7 @@ module_item
       }
   | K_function automatic_opt function_range_or_type_opt IDENTIFIER error K_endfunction
       {
-	pform_pop_scope();
-	current_task = 0;
+	assert(current_function == 0);
 	delete[]$4;
       }
 

pform.cc

@@ -262,6 +262,7 @@ static LexicalScope* lexical_scope = 0;
 
 void pform_pop_scope()
 {
+      assert(lexical_scope);
       lexical_scope = lexical_scope->parent_scope();
 }