Your model name is invalid

I want to create a lava monster but when trying to import the file that I took out of BlockBench in Mcreator, I get "Invalid Model Name" .... I don't know how to solve it and I didn't understand how to do it from the forums that already exist, I'm not an expert in anything of this and less in codes ...
Here is the code for my mob and maybe you know how to fix it.

Code:

// Made with Blockbench 3.5.2
// Exported for Minecraft version 1.12
// Paste this class into your mod and generate all required imports

public class custom_model extends ModelBase {
    private final ModelRenderer PartesCuerpo;
    private final ModelRenderer PartesCabeza;
    private final ModelRenderer PartesCola;

    public custom_model() {
        textureWidth = 64;
        textureHeight = 64;

        PartesCuerpo = new ModelRenderer(this);
        PartesCuerpo.setRotationPoint(0.0F, 24.0F, 0.0F);
        PartesCuerpo.cubeList.add(new ModelBox(PartesCuerpo, 0, 0, -5.0F, -17.0F, -5.0F, 10, 8, 10, 0.0F, false));
        PartesCuerpo.cubeList.add(new ModelBox(PartesCuerpo, 0, 42, -7.0F, -11.0F, 1.0F, 2, 4, 4, 0.0F, false));
        PartesCuerpo.cubeList.add(new ModelBox(PartesCuerpo, 40, 19, 5.0F, -11.0F, 1.0F, 2, 4, 4, 0.0F, false));

        PartesCabeza = new ModelRenderer(this);
        PartesCabeza.setRotationPoint(0.0F, 24.0F, 0.0F);
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 0, 18, -3.0F, -16.0F, -9.0F, 6, 6, 5, 0.0F, false));
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 22, 22, -3.0F, -15.0F, -15.0F, 6, 1, 6, 0.0F, false));
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 0, 29, -3.0F, -11.0F, -14.0F, 6, 1, 5, 0.0F, false));
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 0, 35, 2.0F, -14.0F, -15.0F, 1, 1, 6, 0.0F, false));
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 34, 12, -3.0F, -14.0F, -15.0F, 1, 1, 6, 0.0F, false));
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 0, 0, -2.0F, -14.0F, -15.0F, 4, 1, 1, 0.0F, false));
        PartesCabeza.cubeList.add(new ModelBox(PartesCabeza, 26, 29, -5.0F, -23.0F, -8.0F, 10, 7, 0, 0.0F, false));

        PartesCola = new ModelRenderer(this);
        PartesCola.setRotationPoint(0.0F, 24.0F, 0.0F);
        PartesCola.cubeList.add(new ModelBox(PartesCola, 30, 0, -2.0F, -17.0F, 5.0F, 4, 3, 5, 0.0F, false));
        PartesCola.cubeList.add(new ModelBox(PartesCola, 15, 29, -1.0F, -16.5F, 10.0F, 2, 2, 7, 0.0F, false));
        PartesCola.cubeList.add(new ModelBox(PartesCola, 0, 2, -1.0F, -18.5F, 17.0F, 2, 4, 1, 0.0F, false));
    }

    @Override
    public void render(Entity entity, float f, float f1, float f2, float f3, float f4, float f5) {
        PartesCuerpo.render(f5);
        PartesCabeza.render(f5);
        PartesCola.render(f5);
    }

    public void setRotationAngle(ModelRenderer modelRenderer, float x, float y, float z) {
        modelRenderer.rotateAngleX = x;
        modelRenderer.rotateAngleY = y;
        modelRenderer.rotateAngleZ = z;
    }
}