Anuken/Mindustry · error · IllegalArgumentException

No constructor set up for unit '{name}', add this argument t

Error message

No constructor set up for unit '{name}', add this argument to your units field: `constructor = UnitEntity::create`

What it means

UnitType.createIcons needs a sample entity (sample = constructor.get()) to generate outlines, so it throws IllegalArgumentException if constructor is still null at icon-generation time. This is the same root cause as the init-time check (117) but fires later during createIcons.

Source

Thrown at core/src/mindustry/type/UnitType.java:1220

        for(Weapon weapon : weapons){
            for(var part : weapon.parts){
                part.getOutlines(out);
            }
        }
        for(var part : parts){
            part.getOutlines(out);
        }
    }

    public boolean needsBodyOutline(){
        return alwaysCreateOutline;
    }

    @Override
    public void createIcons(MultiPacker packer){
        super.createIcons(packer);

        if(constructor == null) throw new IllegalArgumentException("No constructor set up for unit '" + name + "', add this argument to your units field: `constructor = UnitEntity::create`");

        sample = constructor.get();

        var toOutline = new Seq<TextureRegion>();
        getRegionsToOutline(toOutline);

        for(var region : toOutline){
            if(region instanceof AtlasRegion atlas && !Core.atlas.has(atlas.name + "-outline")){
                String regionName = atlas.name;
                Pixmap outlined = Pixmaps.outline(packer.get(region), outlineColor, outlineRadius);

                Drawf.checkBleed(outlined);

                packer.add(PageType.main, regionName + "-outline", outlined);
                outlined.dispose();
            }
        }

View on GitHub (pinned to f695ad7e60)

Solutions

Assign constructor for every UnitType (same fix as 117).
Ensure constructor is set before both init and createIcons phases.
Avoid defining UnitTypes that are never fully configured.

Example fix

// before: UnitType with no constructor reaches createIcons -> throws
// after: set constructor = UnitEntity::create (or the appropriate factory) in the type's constructor

Defensive patterns

Strategy: validation

Validate before calling

// Guard createIcons against missing constructors.
if(constructor == null) {
    throw new IllegalArgumentException("No constructor for unit '" + name + "'");
}

Type guard

boolean hasConstructor(UnitType t){ return t != null && t.constructor != null; }

Try / catch

try {
    type.createIcons(packer);
} catch(IllegalArgumentException e) {
    if(e.getMessage().startsWith("No constructor set up for unit")) { /* assign constructor */ }
    else throw e;
}

Prevention

Set constructor on every UnitType so both init and createIcons pass.
Avoid half-defined UnitTypes that reach icon generation.
Reuse the same fix as the init-time constructor check.

When it happens

Trigger: A UnitType reaches createIcons with constructor == null (no factory assigned).

Common situations: A unit type skipped/deferred the init-time check, or constructor was set conditionally and left null; icon generation runs for a half-defined type.

Related errors

AI-assisted analysis of Anuken/Mindustry@f695ad7e60 (2026-08-14). Data as JSON: /api/errors/a2ec335ee2d091a6. Report an issue: GitHub.