use stop_on_error in test case just for coverage.

Author: jacobwilliams

src/tests/jf_test_30.F90

@@ -39,7 +39,7 @@ subroutine test_30(error_cnt)
         write(error_unit,'(A)') 'escape_solidus = '//trim(tf(i))
         write(error_unit,'(A)') ''
 
-        call json%initialize(escape_solidus=(i==1))
+        call json%initialize(escape_solidus=(i==1), stop_on_error=.true.)
         call json%load_from_string(str)
         call json%print_file()