Commit error when splitting several polygons with "array type" attribute (PostGIS / QGIS)

I have a simple PostGIS table :

CREATE TABLE public.elem_p
(
    gid integer NOT NULL DEFAULT nextval('elem_p_gid_seq'::regclass),
    liste character varying[] COLLATE pg_catalog."default" NOT NULL,
    geom geometry(MultiPolygon,2154),
    CONSTRAINT elem_p_pkey PRIMARY KEY (gid)
)

The ‘liste’ field is array-type ;

When I split polygons one-by-one with the QGIS splitting tool, there is no problem.

When I split several polygons that all have at least 2 dimension in the array type "liste", there is no problem …

BUT when I split several polygons that have less than 2 dimensions in the array type "liste" (0 or 1) I have an error like this :

Could not commit changes to layer elem_p

Errors: SUCCESS: 2 geometries were changed. ERROR: 2 feature(s) not
added.
Provider errors:
PostGIS error while adding features: ERREUR: tableau litéral mal formé : « abcd »
DETAIL: La valeur du tableau doit commencer avec « { » ou avec l’information de la
dimension.

(raw translation from french : "wrongly build array : "abcd" ; DETAIL : array value must start with "{" or with information about dimension)

EDIT :
The whole new script :

/* TABLE */ 
DROP TABLE IF EXISTS elem_p CASCADE ; CREATE TABLE elem_p (gid serial, liste varchar[], geom geometry(multipolygon, 2154)) ;
INSERT INTO elem_p (gid, liste, geom) 
VALUES (nextval('elem_p_gid_seq'::regclass), '{E-1, E-5}', ST_MULTI(ST_SETSRID(st_geomfromtext('POLYGON((0 0, 2 0, 2 2, 0 2, 0 0))'), 2154)))
   ,(nextval('elem_p_gid_seq'::regclass), '{E-1, E-7}', ST_MULTI(ST_SETSRID(st_geomfromtext('POLYGON((10 10, 6 6, 6 7, 6 8, 7 10 , 9 10, 10 10))'), 2154)))
   ,(nextval('elem_p_gid_seq'::regclass), NULL, ST_MULTI(ST_SETSRID(st_geomfromtext('POLYGON((0 10, -3 10, -3 8, -5 5, 0 4, 0 10))'), 2154))) ;
UPDATE elem_p  SET liste = '{E-30}'  WHERE gid = 2 ; 

/* VIEW  */
CREATE OR REPLACE VIEW v_elem_p AS (SELECT * FROM elem_p) ;

/*  FUNCTION  */
DROP FUNCTION IF EXISTS maj_elem_p() CASCADE ;
CREATE FUNCTION maj_elem_p() RETURNS TRIGGER AS 
$$   BEGIN 
IF TG_OP = 'INSERT' THEN INSERT INTO elem_p (liste, geom)  VALUES(COALESCE((NEW.liste::varchar)::varchar[], '{}'::varchar[]), NEW.geom); RETURN NEW; END IF;
IF TG_OP = 'UPDATE' THEN UPDATE elem_p SET (liste, geom) = (COALESCE((NEW.liste::varchar)::varchar[], '{}'::varchar[]), NEW.geom) WHERE gid = NEW.gid; RETURN NEW ; END IF ;
END;  
$$  LANGUAGE PLPGSQL ;

/* TRIGGER  */ 
DROP TRIGGER IF EXISTS tg_maj_elem_p  ON v_elem_p ; CREATE TRIGGER tg_maj_elem_p INSTEAD OF INSERT OR UPDATE ON v_elem_p  FOR EACH ROW   EXECUTE PROCEDURE public.maj_elem_p();

/* TESTS */
UPDATE v_elem_p  SET liste = '{E-99}'  WHERE gid = 2 ; 
INSERT INTO v_elem_p VALUES (DEFAULT, '{E-123, E-54}', ST_MULTI(ST_SETSRID(st_geomfromtext('POLYGON((3 3, 5 3, 5 4,5 5, 2 6, 3 3))'), 2154)))

CREATE OR REPLACE VIEW elem_p_v AS
    SELECT  gid,
            ARRAY_TO_STRING(liste, ',') AS liste,
            geom
    FROM    elem_p
;

CREATE OR REPLACE FUNCTION elem_p_v_insert_func()
  RETURNS TRIGGER AS
    $$
    BEGIN
      INSERT INTO elem_p (liste, geom) VALUES
        (REGEXP_SPLIT_TO_ARRAY(NEW.liste, ','), NEW.geom)
      ;
      RETURN NEW;
    END;
    $$
  LANGUAGE 'plpgsql'
;

CREATE TRIGGER elem_p_check_array_literal
  INSTEAD OF INSERT ON elem_p_v
  FOR EACH ROW
  EXECUTE PROCEDURE elem_p_v_insert_func()
;