Shader Initialization Error

I'm relatively new to the topic of Unity shaders, and have hit a problem with initialization (I believe because Unity is using DirectX11)..

The error is "Shader Warning: Output Value 'vert' is not completely initailized on line 46 (on d3d11)" ( https://puu.sh/vTPsU/e1119ad1ec.png ), and here's a copy of the code. If anyone could help me out, I'd greatly appreciate it.

Code (CSharp):

1. // Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
2.  
3. Shader "Custom/FresnelTextureEffect" {
4.  
5. Properties{
6.     _MainTex("Main Texture", 2D) = "white" {}
7.     _Colour("Main Colour", Color) = (1,1,1,1)
8.     _SpecColour("Specular Colour", Color) = (1,1,1,1)
9.     _SpecShininess("Specular Shininess", Range(1.0, 100.0)) = 2.0
10.     _FresnelPower("Fresnel Power", Range(0.0, 3.0)) = 1.4
11.     _FresnelScale("Fresnel Scale", Range(0.0, 1.0)) = 1.0
12.     _FresnelColour("Fresnel Colour", Color) = (1,1,1,1)
13. }
14.  
15. SubShader {
16.     Pass {
17.         Tags {"LightMode" = "ForwardBase"}
18.         CGPROGRAM
19.             #pragma vertex vert
20.             #pragma fragment frag
21.            
22.             #include "UnityCG.cginc"
23.            
24.             struct appdata {
25.                 float4 vertex : POSITION;
26.                 float3 normal : NORMAL;
27.                 float2 texcoord : TEXCOORD0;
28.             };
29.            
30.             struct v2f {
31.                 float4 pos : SV_POSITION;
32.                 float3 normal: NORMAL;
33.                 float2 texcoord : TEXCOORD0;
34.                 float4 posWorld : TEXCOORD1;
35.             };
36.  
37.             float4 _LightColour0;
38.  
39.             float4 _Colour;
40.             sampler2D _MainTex;
41.             float4 _MainTex_ST;
42.  
43.             float4 _SpecColour;
44.             float _SpecShininess;
45.  
46.             v2f vert(appdata IN) {
47.                 v2f OUT;
48.                 OUT.pos = mul(UNITY_MATRIX_MVP, IN.vertex);
49.                 OUT.posWorld = mul(unity_ObjectToWorld, IN.vertex);
50.                 OUT.normal - mul(float4(IN.normal, 0.0), unity_ObjectToWorld).xyz;
51.                 OUT.texcoord = TRANSFORM_TEX(IN.texcoord, _MainTex);
52.                 return OUT;
53.             }
54.  
55.             float4 frag(v2f IN) : COLOR {
56.                 float4 texColour = tex2D(_MainTex, IN.texcoord);
57.                
58.                 float3 normalDirection = normalize(IN.normal);
59.                 float3 lightDirection = normalize(_WorldSpaceLightPos0.xyz);
60.                 float3 viewDirection = normalize(_WorldSpaceCameraPos - IN.posWorld.xyz);
61.                 float3 diffuse = _LightColour0.rgb * _Colour.rgb * max(0.0, dot(normalDirection, lightDirection));
62.  
63.                 float3 specular;
64.                 if (dot(normalDirection, lightDirection) < 0.0) { specular = float3(0.0, 0.0, 0.0); }
65.                 else {
66.                     specular = _LightColour0.rgb * _SpecColour.rgb * pow(max(0.0, dot(reflect(-lightDirection, normalDirection), viewDirection)), _SpecShininess);
67.                 }
68.  
69.                 float3 diffuseSpecular = diffuse + specular;
70.                 return float4(diffuseSpecular, 1) * texColour;
71.             }
72.  
73.         ENDCG
74.     }
75. }
76.  
77. }