Guard against empty ResourceHandler in getFluid

[Copilot]

FluidUtil.getStack(fluidHandler, 0) crashes when the handler has zero slots. Added a size() > 0 guard so an empty handler returns FluidStack.EMPTY instead.

// Before
return fluidHandler != null ? FluidUtil.getStack(fluidHandler, 0) : FluidStack.EMPTY;

// After
return fluidHandler != null && fluidHandler.size() > 0 ? FluidUtil.getStack(fluidHandler, 0) : FluidStack.EMPTY;

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[coveralls]

coverage: 30.841% (-0.004%) from 30.845% — copilot/add-resourcehandler-size-check into master-26