Added visual feedback for shader error

addons/material_maker/engine/shader_material.gd

@@ -16,6 +16,10 @@ func set_shader(shader_code : String) -> bool:
 	var shader : Shader = Shader.new()
 	shader.code = shader_code
 	material.shader = shader
+	if material.shader.get_shader_uniform_list().is_empty():
+		material.shader = preload("res://material_maker/panels/preview_2d/shader_error.gdshader")
+		material.set_shader_parameter("error_tex", preload("res://material_maker/panels/preview_2d/shader_error.png"))
+		return true
 	return true
 
 func get_parameters() -> Dictionary:

material_maker/panels/preview_2d/shader_error.gdshader

@@ -0,0 +1,16 @@
+shader_type canvas_item;
+uniform sampler2D error_tex;
+
+float hash12(vec2 p) {
+	vec3 p3  = fract(vec3(p.xyx) * .1031);
+    p3 += dot(p3, p3.yzx + 33.33);
+    return fract((p3.x + p3.y) * p3.z);
+}
+
+void fragment() {
+	vec2 uv = UV;
+	vec2 s = fwidth(uv);
+	uv = (uv-0.5) * max(s.x,s.y)/s + 0.5;
+	float grain = hash12(floor(uv*512.0) + floor(TIME*24.0)*0.04);
+	COLOR = vec4(texture(error_tex, uv).rgb+grain-0.7, 1.0);
+}

material_maker/panels/preview_2d/shader_error.gdshader.uid

@@ -0,0 +1 @@
+uid://b4y52prpq2j3n

material_maker/panels/preview_2d/shader_error.png.import

@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://bgsenxed4lq0"
+path="res://.godot/imported/shader_error.png-5cf4c3a93958a86da5be4103bc1b1070.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://material_maker/panels/preview_2d/shader_error.png"
+dest_files=["res://.godot/imported/shader_error.png-5cf4c3a93958a86da5be4103bc1b1070.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1