The generator matrix

 1  0  0  0  1  1  1  1  1  X  1  1  1  1  1  1 (a+1)X  1  1 aX  1  1  1 aX  1  1  1 (a+1)X  0  1  1 (a+1)X  1  1  0  1  1 aX  1  1  1  1  1  1 (a+1)X  1  1  1  1  1  0  1  1  1  0  1  1  1  1
 0  1  0  0  0  X  X (a+1)X+1 aX+1  1 aX+a a+1 X+a (a+1)X+a+1  1  X (a+1)X  a  a  1 a+1 X+a  0  1  X X+a (a+1)X+a  1  1 (a+1)X+a+1 a+1  1 X+a+1 (a+1)X+a  1 aX+1 (a+1)X+1  0 (a+1)X X+a  1 aX+a X+a+1  a  1 aX (a+1)X+1  1 (a+1)X+a+1 a+1  1  0  1 (a+1)X+1  1 (a+1)X+a+1 aX+a (a+1)X+a X+1
 0  0  1  0  1 (a+1)X+a (a+1)X+a+1  X aX+a aX+a aX  0 aX+a+1 aX+1 a+1 X+a  1 aX+1 (a+1)X+a X+a  X  X  0 (a+1)X+a a+1 aX+a+1 aX+a+1 aX+a+1  X (a+1)X a+1 a+1 aX+a+1 aX (a+1)X+1 X+1 X+a+1  1  X X+1 (a+1)X+1  a (a+1)X+1 (a+1)X+a  X a+1  a aX+1 aX (a+1)X+1 X+a a+1 aX (a+1)X+1  0 X+1 X+a+1  a  a
 0  0  0  1 a+1  a  1 (a+1)X+a aX (a+1)X+a (a+1)X+1 X+a+1  a aX+a  0 aX  1 aX+1 aX+1 (a+1)X X+1 (a+1)X+a a+1 X+1  X aX+a+1 (a+1)X+1 X+a X+1 (a+1)X+a aX aX X+1 aX+a+1 (a+1)X+a (a+1)X a+1 X+a aX+a aX+a aX+1  a (a+1)X+a (a+1)X+a+1 aX+a+1 (a+1)X (a+1)X+a+1 aX+a+1  0 aX+a+1  0  a aX+1 (a+1)X+a+1 aX+a  X aX aX+a+1  a
 0  0  0  0  X  0 aX  0  0  0 aX  X aX  X aX  X aX  X (a+1)X aX (a+1)X  X (a+1)X aX  X  X  0 (a+1)X  X  0  0  X  X (a+1)X aX  X (a+1)X  0 (a+1)X aX (a+1)X  0 aX  0 (a+1)X (a+1)X (a+1)X  0  0 aX  X  0  X aX (a+1)X  0  0  X (a+1)X

generates a code of length 59 over F4[X,sigma]/(X^2) who´s minimum homogenous weight is 158.

Homogenous weight enumerator: w(x)=1x^0+588x^158+516x^159+753x^160+1188x^161+2424x^162+2136x^163+2376x^164+3372x^165+6120x^166+4980x^167+4794x^168+6240x^169+11508x^170+8676x^171+7251x^172+10908x^173+17376x^174+12336x^175+10212x^176+15096x^177+22932x^178+15108x^179+9825x^180+13716x^181+17832x^182+11556x^183+7782x^184+8496x^185+9900x^186+5004x^187+3339x^188+2148x^189+3204x^190+1044x^191+615x^192+276x^193+276x^194+84x^195+75x^196+42x^200+21x^204+9x^208+6x^212+3x^220

The gray image is a linear code over GF(4) with n=236, k=9 and d=158.
This code was found by Heurico 1.16 in 228 seconds.