The following errors pop up from time to time. When I imported the NPM package for the first time and also after I imported an unrelated 3rd party plugin Odin Inspector. Doesn't seem to pop up on domain reload though and the errors otherwise do clear.
Latest Spine 4.1 and latest NPM runtimes. Unity 2021.3.6f1.
Shader error in 'Universal Render Pipeline/2D/Spine/Skeleton Lit': Couldn't open include file 'Packages/com.esotericsoftware.spine.spine-unity/Runtime/spine-unity/Shaders/CGIncludes/Spine-Common.cginc'. at /GameDev/Dungeon Tavern/Library/PackageCache/com.esotericsoftware.spine.urp-shaders@2ef38e4f01/Shaders/Include/SpineCoreShaders/Spine-Common.cginc(2)
Compiling Subshader: 0, Pass: <Unnamed Pass 0>, Vertex program with <no keywords>
Platform defines: SHADER_API_DESKTOP UNITY_COLORSPACE_GAMMA UNITY_ENABLE_DETAIL_NORMALMAP UNITY_ENABLE_REFLECTION_BUFFERS UNITY_LIGHTMAP_FULL_HDR UNITY_LIGHT_PROBE_PROXY_VOLUME UNITY_PBS_USE_BRDF1 UNITY_SPECCUBE_BLENDING UNITY_SPECCUBE_BOX_PROJECTION UNITY_USE_DITHER_MASK_FOR_ALPHABLENDED_SHADOWS
Disabled keywords: SHADER_API_GLES30 UNITY_ASTC_NORMALMAP_ENCODING UNITY_ENABLE_NATIVE_SHADOW_LOOKUPS UNITY_FRAMEBUFFER_FETCH_AVAILABLE UNITY_HALF_PRECISION_FRAGMENT_SHADER_REGISTERS UNITY_HARDWARE_TIER1 UNITY_HARDWARE_TIER2 UNITY_HARDWARE_TIER3 UNITY_LIGHTMAP_DLDR_ENCODING UNITY_LIGHTMAP_RGBM_ENCODING UNITY_METAL_SHADOWS_USE_POINT_FILTERING UNITY_NO_DXT5nm UNITY_NO_FULL_STANDARD_SHADER UNITY_NO_SCREENSPACE_SHADOWS UNITY_PBS_USE_BRDF2 UNITY_PBS_USE_BRDF3 UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION UNITY_UNIFIED_SHADER_PRECISION_MODEL UNITY_VIRTUAL_TEXTURING USE_SHAPE_LIGHT_TYPE_0 USE_SHAPE_LIGHT_TYPE_1 USE_SHAPE_LIGHT_TYPE_2 USE_SHAPE_LIGHT_TYPE_3 _LIGHT_AFFECTS_ADDITIVE _STRAIGHT_ALPHA_INPUT
Shader error in 'Universal Render Pipeline/Spine/Skeleton Lit': Couldn't open include file 'Packages/com.esotericsoftware.spine.spine-unity/Runtime/spine-unity/Shaders/CGIncludes/Spine-Common.cginc'. at /GameDev/Dungeon Tavern/Library/PackageCache/com.esotericsoftware.spine.urp-shaders@2ef38e4f01/Shaders/Include/SpineCoreShaders/Spine-Common.cginc(2)
Compiling Subshader: 0, Pass: ForwardLit, Vertex program with _RECEIVE_SHADOWS_OFF
Platform defines: SHADER_API_DESKTOP UNITY_COLORSPACE_GAMMA UNITY_ENABLE_DETAIL_NORMALMAP UNITY_ENABLE_REFLECTION_BUFFERS UNITY_LIGHTMAP_FULL_HDR UNITY_LIGHT_PROBE_PROXY_VOLUME UNITY_PBS_USE_BRDF1 UNITY_SPECCUBE_BLENDING UNITY_SPECCUBE_BOX_PROJECTION UNITY_USE_DITHER_MASK_FOR_ALPHABLENDED_SHADOWS
Disabled keywords: FOG_EXP FOG_EXP2 FOG_LINEAR INSTANCING_ON SHADER_API_GLES30 UNITY_ASTC_NORMALMAP_ENCODING UNITY_ENABLE_NATIVE_SHADOW_LOOKUPS UNITY_FRAMEBUFFER_FETCH_AVAILABLE UNITY_HALF_PRECISION_FRAGMENT_SHADER_REGISTERS UNITY_HARDWARE_TIER1 UNITY_HARDWARE_TIER2 UNITY_HARDWARE_TIER3 UNITY_LIGHTMAP_DLDR_ENCODING UNITY_LIGHTMAP_RGBM_ENCODING UNITY_METAL_SHADOWS_USE_POINT_FILTERING UNITY_NO_DXT5nm UNITY_NO_FULL_STANDARD_SHADER UNITY_NO_SCREENSPACE_SHADOWS UNITY_PBS_USE_BRDF2 UNITY_PBS_USE_BRDF3 UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION UNITY_UNIFIED_SHADER_PRECISION_MODEL UNITY_VIRTUAL_TEXTURING _ADDITIONAL_LIGHTS _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHT_SHADOWS _DOUBLE_SIDED_LIGHTING _LIGHT_AFFECTS_ADDITIVE _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MIXED_LIGHTING_SUBTRACTIVE _RECEIVE_SHADOWS _SHADOWS_SOFT _STRAIGHT_ALPHA_INPUT
Shader error in 'Universal Render Pipeline/Spine/Skeleton': Couldn't open include file 'Packages/com.esotericsoftware.spine.spine-unity/Runtime/spine-unity/Shaders/CGIncludes/Spine-Common.cginc'. at /GameDev/Dungeon Tavern/Library/PackageCache/com.esotericsoftware.spine.urp-shaders@2ef38e4f01/Shaders/Include/SpineCoreShaders/Spine-Common.cginc(2)
Compiling Subshader: 0, Pass: Forward, Fragment program with <no keywords>
Platform defines: SHADER_API_DESKTOP UNITY_COLORSPACE_GAMMA UNITY_ENABLE_DETAIL_NORMALMAP UNITY_ENABLE_REFLECTION_BUFFERS UNITY_LIGHTMAP_FULL_HDR UNITY_LIGHT_PROBE_PROXY_VOLUME UNITY_PBS_USE_BRDF1 UNITY_SPECCUBE_BLENDING UNITY_SPECCUBE_BOX_PROJECTION UNITY_USE_DITHER_MASK_FOR_ALPHABLENDED_SHADOWS
Disabled keywords: FOG_EXP FOG_EXP2 FOG_LINEAR INSTANCING_ON SHADER_API_GLES30 UNITY_ASTC_NORMALMAP_ENCODING UNITY_ENABLE_NATIVE_SHADOW_LOOKUPS UNITY_FRAMEBUFFER_FETCH_AVAILABLE UNITY_HALF_PRECISION_FRAGMENT_SHADER_REGISTERS UNITY_HARDWARE_TIER1 UNITY_HARDWARE_TIER2 UNITY_HARDWARE_TIER3 UNITY_LIGHTMAP_DLDR_ENCODING UNITY_LIGHTMAP_RGBM_ENCODING UNITY_METAL_SHADOWS_USE_POINT_FILTERING UNITY_NO_DXT5nm UNITY_NO_FULL_STANDARD_SHADER UNITY_NO_SCREENSPACE_SHADOWS UNITY_PBS_USE_BRDF2 UNITY_PBS_USE_BRDF3 UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION UNITY_UNIFIED_SHADER_PRECISION_MODEL UNITY_VIRTUAL_TEXTURING _ADDITIONAL_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _SHADOWS_SOFT _STRAIGHT_ALPHA_INPUT
Shader error in 'Universal Render Pipeline/2D/Spine/Sprite': Couldn't open include file 'Packages/com.esotericsoftware.spine.spine-unity/Runtime/spine-unity/Shaders/Sprite/CGIncludes/ShaderShared.cginc'. at /GameDev/Dungeon Tavern/Library/PackageCache/com.esotericsoftware.spine.urp-shaders@2ef38e4f01/Shaders/Include/SpineCoreShaders/ShaderShared.cginc(2)
Compiling Subshader: 0, Pass: <Unnamed Pass 0>, Fragment program with <no keywords>
Platform defines: SHADER_API_DESKTOP UNITY_COLORSPACE_GAMMA UNITY_ENABLE_DETAIL_NORMALMAP UNITY_ENABLE_REFLECTION_BUFFERS UNITY_LIGHTMAP_FULL_HDR UNITY_LIGHT_PROBE_PROXY_VOLUME UNITY_PBS_USE_BRDF1 UNITY_SPECCUBE_BLENDING UNITY_SPECCUBE_BOX_PROJECTION UNITY_USE_DITHER_MASK_FOR_ALPHABLENDED_SHADOWS
Disabled keywords: INSTANCING_ON PIXELSNAP_ON SHADER_API_GLES30 UNITY_ASTC_NORMALMAP_ENCODING UNITY_ENABLE_NATIVE_SHADOW_LOOKUPS UNITY_FRAMEBUFFER_FETCH_AVAILABLE UNITY_HALF_PRECISION_FRAGMENT_SHADER_REGISTERS UNITY_HARDWARE_TIER1 UNITY_HARDWARE_TIER2 UNITY_HARDWARE_TIER3 UNITY_LIGHTMAP_DLDR_ENCODING UNITY_LIGHTMAP_RGBM_ENCODING UNITY_METAL_SHADOWS_USE_POINT_FILTERING UNITY_NO_DXT5nm UNITY_NO_FULL_STANDARD_SHADER UNITY_NO_SCREENSPACE_SHADOWS UNITY_PBS_USE_BRDF2 UNITY_PBS_USE_BRDF3 UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION UNITY_UNIFIED_SHADER_PRECISION_MODEL UNITY_VIRTUAL_TEXTURING USE_SHAPE_LIGHT_TYPE_0 USE_SHAPE_LIGHT_TYPE_1 USE_SHAPE_LIGHT_TYPE_2 USE_SHAPE_LIGHT_TYPE_3 _ADDITIVEBLEND _ADDITIVEBLEND_SOFT _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON _ALPHAPREMULTIPLY_VERTEX_ONLY _ALPHA_CLIP _COLOR_ADJUST _EMISSION _FIXED_NORMALS_MODELSPACE _FIXED_NORMALS_MODELSPACE_BACKFACE _FIXED_NORMALS_VIEWSPACE _FIXED_NORMALS_VIEWSPACE_BACKFACE _LIGHT_AFFECTS_ADDITIVE _MULTIPLYBLEND _MULTIPLYBLEND_X2 _NORMALMAP _RIM_LIGHTING _STRAIGHT_ALPHA_INPUT _TEXTURE_BLEND