When viewing the submissions of any assignment that has the Grade Type of None a coding exception is thrown because /mod/assign/locallib.php attempts to get the decimals of grade when there is no grade. Changing the assignment to Grade Type Point enables you to view the submissions page.

1. View an assignment of grade type None that has submissions.
2. Click on "View/grade all submissions"

Debug info:
Error code: codingerror
Stack trace:
line 1220 of /mod/assign/locallib.php: coding_exception thrown
line 1332 of /mod/assign/locallib.php: call to assign->get_grade_item()
line 639 of /mod/assign/gradingtable.php: call to assign->display_grade()
line 861 of /mod/assign/gradingtable.php: call to assign_grading_table->display_grade()
line 817 of /lib/tablelib.php: call to assign_grading_table->col_grade()
line 463 of /mod/assign/gradingtable.php: call to flexible_table->format_row()
line 1521 of /lib/tablelib.php: call to assign_grading_table->format_row()
line 1638 of /lib/tablelib.php: call to table_sql->build_table()
line 1233 of /mod/assign/renderer.php: call to table_sql->out()
line 1029 of /mod/assign/renderer.php: call to mod_assign_renderer->flexible_table()
line 319 of /lib/outputrenderers.php: call to mod_assign_renderer->render_assign_grading_table()
line 3412 of /mod/assign/locallib.php: call to plugin_renderer_base->render()
line 3450 of /mod/assign/locallib.php: call to assign->view_grading_table()
line 552 of /mod/assign/locallib.php: call to assign->view_grading_page()
line 52 of /mod/assign/view.php: call to assign->view()

Version 3.0.7 vs 3.0.6 introduced the following code on line 1332 of /mod/assign/locallib.php

$decimals = $this->get_grade_item()->get_decimals();