Updating a virtual column corrupts table which crashes server

DROP TABLE IF EXISTS grad_degree;

CREATE TABLE IF NOT EXISTS grad_degree (

  student_id int(8) UNSIGNED NOT NULL,

	plan varchar(10) NOT NULL,

  admit_term char(4) NOT NULL,

  faculty varchar(3) NOT NULL DEFAULT '',

  org_unit varchar(4) NOT NULL DEFAULT '',

  registered char(1) NOT NULL DEFAULT '',

  ft_pt enum('F', 'P') NOT NULL,

  level char(1) NOT NULL DEFAULT '',

  enrl_type varchar(4) NOT NULL DEFAULT '',

  curr_term decimal(3,1) UNSIGNED NOT NULL DEFAULT '0.0',

  cum_term decimal(3,1) UNSIGNED NOT NULL DEFAULT '0.0',

  wdraw_code varchar(3) NOT NULL DEFAULT '',

  wdraw_rsn varchar(4) NOT NULL DEFAULT '',

	wdraw_date date NOT NULL DEFAULT '0000-00-00',

  term_gpa decimal(5,2) UNSIGNED NOT NULL DEFAULT '0.00',

  cum_gpa decimal(5,2) UNSIGNED NOT NULL DEFAULT '0.00',

  thesis_title varchar(250) NOT NULL DEFAULT '',

  ofis_deg_status varchar(15) AS (

		CASE

			WHEN wdraw_rsn = '' THEN 'In progress'

			WHEN wdraw_rsn = 'DCMP' OR wdraw_rsn = 'TRDC' THEN 'Completed'

			ELSE 'Not Completed'

		END) VIRTUAL,

	deg_transferred enum('Y', 'N') NOT NULL DEFAULT 'N' COMMENT 'Guessed by the same admit term with a different plan for a student', 

  deg_start_term char(4) NOT NULL DEFAULT '' COMMENT 'Educated guess at the beginning of the data', 

  deg_as_of_term char(4) NOT NULL COMMENT 'In most cases also end term', 

  CONSTRAINT grad_degree_stu_plan_admit_pky PRIMARY KEY (student_id, plan, admit_term)

) ENGINE  = InnoDB  DEFAULT CHARSET  = utf8

;

CREATE INDEX grad_degree_wdraw_rsn_ndx ON grad_degree (wdraw_rsn);

CREATE INDEX grad_degree_admit_term_ndx ON grad_degree (admit_term);

CREATE INDEX grad_degree_as_of_term_ndx ON grad_degree (deg_as_of_term);

UPDATE grad_degree AS gd 

INNER JOIN

        gso_grad_supr AS ggs 

        ON ( gd.student_id = ggs.uw_id AND gd.plan = ggs.plan AND gd.admit_term = ggs.admit_term )

SET 

    gd.faculty = ggs.faculty,

    gd.org_unit = ggs.org_unit,

    gd.registered = ggs.registered,

    gd.ft_pt = ggs.ft_pt,

    gd.level = ggs.level,

    gd.enrl_type = ggs.enrl_type,

    gd.curr_term = ggs.curr_term,

    gd.cum_term = ggs.cum_term,

    gd.wdraw_code = ggs.wdraw_code,

    gd.wdraw_rsn = ggs.wdraw_rsn,

    gd.wdraw_date = ggs.wdraw_date,

    gd.term_gpa = ggs.term_gpa,

    gd.cum_gpa = ggs.cum_gpa,

    gd.deg_as_of_term = 1031 

WHERE

        gd.wdraw_rsn NOT IN ('DCMP', 'TRDC') AND 

	ggs.term = 1031 

;