Shader error : unexpected $end, expecting TOK_SETTEXTURE or '}' at line 18

I was writing a simple shader which could render a cuboid wireframe of the mesh. However, after compiled the shader, Unity gave out the following error:

Shader error in 'CuboidWireframeShader': Parse error: syntax error, unexpected $end, expecting TOK_SETTEXTURE or '}' at line 18

I am confused because at this line, Because there is only a CGPROGRAMn token. The full shader code is shown below:

 Shader "Custom/CuboidWireframeShader"
 {
     Properties
     {
         _Color ("Color", Color) = (1,1,1,1)
         _MainTex ("Main Texture", 2D) = "white" {}
         _Thickness ("Thickness", Float) = 1
     }
     
     SubShader
     {
         Pass
         {
             Tags { "RenderType"="Opaque" "Queue"="Geometry" }
             Blend SrcAlpha OneMinusSrcAlpha
             Cull Off
             
             CGPROGRAM
 
             #pragma target 4.0
             #pragma vertex vert
             #pragma fragment frag
             #pragma geometry geom
             #include "UnityCG.cginc"
             
             float _Thickness;
             float4 _Color;
             float4 _MainTex_ST;
             sampler2D _MainTex;
             
             struct v2g {
                 float4 pos : POSITION;
                 float2 uv : TEXCOORD0;
             }
             
             struct g2f {
                 float4 pos : POSITION;
                 float2 uv : TEXCOORD0;
                 float3 distance : TEXCOORD1;
             }
             
             v2g vert(appdata_base v) {
                 v2g o;
                 o.pos = UnityObjectToClipPos(v.vertex);
                 o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
                 return o;
             }
             
             [maxvertexcount(3)]
             void geom(triangle v2g p[3], inout TriangleStream<g2f> triStream) {
                 v2g np[3];
                 bool find = false;
                 for (int i = 0; i < 3 && !find; i++) {
                     for (int j = i + 1; j < 3 && !find; j++) {
                         if (abs(p[i].uv.x - p[j].uv.x) > 0.01f && abs(p[i].uv.y - p[j].uv.y) > 0.01f) {
                             np[0] = p[3 - i - j];
                             np[1] = p[i];
                             np[2] = p[j];
                             find = true;
                         }
                     }
                 }
                 
                 float2 p0 = _ScreenParams.xy * np[0].pos.xy / np[0].pos.w;
                 float2 p1 = _ScreenParams.xy * np[1].pos/xy / np[1].pos.w;
                 float2 p2 = _ScreenParams.xy * np[2].pos/xy / np[2].pos.w;  
                 float2 v0 = p2 - p1;
                 float2 v1 = p2 - p0;
                 float2 v2 = p1 - p0;                   
                 float area = abs(v1.x * v2.y - v1.y * v2.x);                 
                 float dist0 = area / length(v0);
                 float dist1 = area / length(v1);
                 float dist2 = area / length(v2);
                                
                 g2f pIn;
                 pIn.pos = np[0].pos;
                 pIn.uv = np[0].uv;
                 pIn.dist = float3(dist0, 0, 0);
                 triStream.Append(pIn);
                 
                 pIn.pos = np[1].pos;
                 pIn.uv = np[1].uv;
                 pIn.dist = float3(0, dist1, 0);
                 triStream.Append(pIn);
                 
                 pIn.pos = np[2].pos;
                 pIn.uv = np[2].uv;
                 pIn.dist = float3(0, 0, dist2);
                 triStream.Append(pIn);
             }
             
             float4 frag(g2f input) : COLOR {
                 float4 color = _Color * tex2D(_MainTex, input.uv);
                 float4 transColor = float4(0, 0, 0, 0);
                 color = (_Thickness > input.dist.y || _Thickness  > input.dist.z) ? targetColor : transColor;
                 if(color.a < 0.5f) discard;
                 else color.a = 1.0f;
                 return color;
             }
 
             ENDCG
         }
     }
 }

What have I done wrong with this shader? Thanks for helping!