Undeclared identifier free 2D shader on the asset store.

I use the free 2D GPU lightning system from the asset store : https://www.assetstore.unity3d.com/en/#!/content/30953

It works fine in the editor but when I try to compile and build the game, the following errors appear in the console and the build fail instantly : Shader error in 'Light2D/Light Auto Points': undeclared identifier 'PATH_TRACKING_SAMPLES' at Assets/Light2D/Resources/Shaders/LightBase.cginc(93) (on d3d9)

Shader error in 'Light2D/Light Auto Points': undeclared identifier 'PATH_TRACKING_SAMPLES' at Assets/Light2D/Resources/Shaders/LightBase.cginc(93) (on d3d11)

Here's the script:

 // Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
 // Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
 
 /*
 
 Base code for standard light shaders.
 Light is computed by path tracking with fixed number of steps (PATH_TRACKING_SAMPLES).
 
 */
 
 
 #ifndef LIGHT_BASE_INCLUDED
 #define LIGHT_BASE_INCLUDED
 
 #pragma glsl_no_auto_normalization
 
 struct light2d_fixed_data_t {
     float4 vertex : POSITION;
     float2 texcoord : TEXCOORD0;
     float4 color : COLOR0;
     float2 texcoord1 : TEXCOORD1;
 };
 
 struct light2d_fixed_v2f {
     float4 vertex : SV_POSITION;
     half2 texcoord : TEXCOORD0;
     half4 color : COLOR0;
     #ifdef PERSPECTIVE_CAMERA
     half2 texcoord1 : TEXCOORD1;
     float4 projVertex : COLOR1;
     float zDistance : TEXCOORD2;
     #else
     half2 thisPos : TEXCOORD2;
     half2 centerPos : TEXCOORD1;
     #endif
     half2 aspect : TEXCOORD3;
 };
             
 uniform sampler2D _ObstacleTex;
 uniform sampler2D _MainTex;
 uniform half _ObstacleMul;
 uniform half _EmissionColorMul;
 uniform float2 _ExtendedToSmallTextureScale;
 #ifdef UNITY_HALF_TEXEL_OFFSET
 uniform half2 _PosOffset;
 #endif
 
 light2d_fixed_v2f light2d_fixed_vert (light2d_fixed_data_t v)
 {
     light2d_fixed_v2f o;
     o.vertex = UnityObjectToClipPos(v.vertex);
     o.texcoord = v.texcoord;
 
     #ifdef PERSPECTIVE_CAMERA
     o.texcoord1 = v.texcoord1;
     o.projVertex = o.vertex;
     o.zDistance = mul(unity_ObjectToWorld, v.vertex).z;
     #else
     float4 vPos = ComputeScreenPos(o.vertex);
     o.thisPos = (vPos.xy/vPos.w - 0.5)*_ExtendedToSmallTextureScale + 0.5;
     float4 cPos = ComputeScreenPos(mul(UNITY_MATRIX_VP, float4(v.texcoord1, 0, 1)));
     o.centerPos = (cPos.xy/cPos.w - 0.5)*_ExtendedToSmallTextureScale + 0.5;
     #ifdef UNITY_HALF_TEXEL_OFFSET
     o.thisPos += _PosOffset;
     o.centerPos += _PosOffset;
     #endif
     #endif
 
     o.color = v.color;
     o.aspect = half2(_ScreenParams.x/_ScreenParams.y, 1);
 
     return o;
 }
 
 half4 light2_fixed_frag (light2d_fixed_v2f i) : COLOR
 {
     half4 tex = tex2D(_MainTex, i.texcoord);
 
     #ifdef PERSPECTIVE_CAMERA
     half4 vPos = ComputeScreenPos(i.projVertex);
     half2 thisPos = (vPos.xy/vPos.w - 0.5)*_ExtendedToSmallTextureScale + 0.5;
     half4 cPos = ComputeScreenPos(mul(UNITY_MATRIX_VP, float4(i.texcoord1, i.zDistance, 1)));
     half2 centerPos = (cPos.xy/cPos.w - 0.5)*_ExtendedToSmallTextureScale + 0.5;
     #ifdef UNITY_HALF_TEXEL_OFFSET
     thisPos += _PosOffset;
     centerPos += _PosOffset;
     #endif
     #else
     half2 thisPos = i.thisPos;
     half2 centerPos = i.centerPos;
     #endif
 
     half sub = 1.0/PATH_TRACKING_SAMPLES;
     half len = length((thisPos - centerPos)*i.aspect);
     half m = _ObstacleMul*sub*len;
             
     half4 col = i.color*tex*tex.a*i.color.a;
 
     half pos = 0;
     
     for(int i = 0; i < PATH_TRACKING_SAMPLES; i++)
     {
         pos += sub; 
         half4 obstacle = tex2D(_ObstacleTex, lerp(centerPos, thisPos, pos));
         col *= saturate(1 - (1 - obstacle)*obstacle.a*m);
     }
 
     col.rgb *= _EmissionColorMul;
 
     return col;//half4(half3((thisPos - centerPos).x*20), 1);//tex2D(_ObstacleTex, thisPos);
 }
 
 #endif