Splatmap shader help needed, problems with roughness

Hello wonderful Godot community! I have been trying to make a terrain for my game made the mesh separated into chunks, Wrote a little LOD script and so on. But came across a problem when I was writing a shader for my terrain. I'm using the splat map method and mixing different sets of textures, preferably I want to mix Albedo, Normal and Roughness. But have a problem doing that with Roughness maps.

Here's the code example to make things more clear:

    shader_type spatial;
    render_mode cull_disabled;
	
    uniform sampler2D splatmap;
    uniform sampler2D tex_base;
    uniform sampler2D tex_r;
    uniform sampler2D tex_g;
    uniform sampler2D tex_b;
    uniform sampler2D tex_a;
	
    uniform sampler2D norm_base;
    uniform sampler2D norm_r;
    uniform sampler2D norm_g;
    uniform sampler2D norm_b;
    uniform sampler2D norm_a;
	
    uniform sampler2D rough_base;
    uniform sampler2D rough_r;
    uniform sampler2D rough_g;
    uniform sampler2D rough_b;
    uniform sampler2D rough_a;
	
	
    uniform float base_res = 5; 
    uniform float r_res = 5; 
    uniform float g_res = 5;
    uniform float b_res = 5;
    uniform float a_res = 5;
	
	
    void fragment() {
		
        vec3 base_col;
        vec3 r_col;
        vec3 g_col;
        vec3 b_col;
        vec3 a_col;
		
	vec3 base_norm;
        vec3 r_norm;
        vec3 g_norm;
        vec3 b_norm;
        vec3 a_norm;
		
	vec3 base_rough;
        vec3 r_rough;
        vec3 g_rough;
        vec3 b_rough;
        vec3 a_rough;
		
        vec4 texs=texture(splatmap,UV);
        float rval = texs.r;
        float gval = texs.g;
        float bval = texs.b;
        float aval = 1.0-texs.a;
		
        float baseval = max(0.0,1.0-(rval+gval+bval+aval));
		
        base_col = texture(tex_base,UV*base_res).rgb * baseval;
        r_col = texture(tex_r,UV*r_res).rgb * rval;
        g_col = texture(tex_g,UV*g_res).rgb * gval;
        b_col = texture(tex_b,UV*b_res).rgb * bval;
        a_col = texture(tex_a,UV*a_res).rgb * aval;
		
        ALBEDO = base_col + r_col + g_col + b_col + a_col;
		
	base_norm = texture(norm_base,UV*base_res).rgb * baseval;
	r_norm = texture(norm_r,UV*r_res).rgb * rval;
	g_norm = texture(norm_g,UV*g_res).rgb * gval;
	b_norm = texture(norm_b,UV*b_res).rgb * bval;
        a_norm = texture(norm_a,UV*a_res).rgb * aval;
		
	NORMALMAP = base_norm + r_norm + g_norm + b_norm + a_norm;
 
 	base_rough = texture(rough_base,UV*base_res).rgb * baseval;
 	r_rough = texture(rough_r,UV*r_res).rgb * rval;
 	g_rough = texture(rough_g,UV*g_res).rgb * gval;
 	b_rough = texture(rough_b,UV*b_res).rgb * bval;
a_rough = texture(rough_a,UV*a_res).rgb * aval;
		
	ROUGHNESS = base_rough + r_rough + g_rough + b_rough + a_rough;

    }

naturally upon running the code I get an error:

:81 - Invalid arguments to operator '=' :float and vec3

Is there a way to mix roughness maps or I can only use a float value in the code? Which will basically assign the same value for every different texture set and will kill the whole point of using splat maps in a way... If someone has an answer to this please let me know...

If I remove the roughness part and only retain a line something like ROUGHNESS = 0.5 it will run perfectly, but it's a float value for all the texture which kills the whole look to be honest.