Addressed PR's comments.

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/Lighting.hlsl

 half4 GetLightDirectionAndAttenuation(LightInput lightInput, float3 positionWS)
 {
     half4 directionAndAttenuation;
-    float3 posToLightVec = lightInput.position.xyz - positionWS.xyz * lightInput.position.w;
+    float3 posToLightVec = lightInput.position.xyz - positionWS * lightInput.position.w;
     float distanceSqr = max(dot(posToLightVec, posToLightVec), FLT_MIN);
 
     directionAndAttenuation.xyz = half3(posToLightVec * rsqrt(distanceSqr));
 
 Light GetMainLight()
 {
-    Light light = (Light)0;
+    Light light;
+    light.index = 0;
     light.direction = _MainLightPosition.xyz;
     light.attenuation = 1.0;
     light.subtractiveModeAttenuation = _MainLightPosition.w;

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/Shadows.hlsl

     half4 shadowOffset1;
     half4 shadowOffset2;
     half4 shadowOffset3;
-    half4 shadowmapSize;
+    float4 shadowmapSize;
 };
 
 ShadowSamplingData GetMainLightShadowSamplingData()