Fixed invocation of storm without a model.

src/storm-cli-utilities/model-handling.h

@@ -289,12 +289,14 @@ namespace storm {
             
             // Set whether a transformation to jani is required or necessary
             mpi.transformToJani = ioSettings.isPrismToJaniSet();
+            if (input.model) {
                 auto builderType = storm::utility::getBuilderType(mpi.engine);
                 bool transformToJaniForJit = builderType == storm::builder::BuilderType::Jit;
                 STORM_LOG_WARN_COND(mpi.transformToJani || !transformToJaniForJit, "The JIT-based model builder is only available for JANI models, automatically converting the PRISM input model.");
                 bool transformToJaniForDdMA = (builderType == storm::builder::BuilderType::Dd) && (input.model->getModelType() == storm::storage::SymbolicModelDescription::ModelType::MA);
                 STORM_LOG_WARN_COND(mpi.transformToJani || !transformToJaniForDdMA, "Dd-based model builder for Markov Automata is only available for JANI models, automatically converting the PRISM input model.");
                 mpi.transformToJani |= (transformToJaniForJit || transformToJaniForDdMA);
+            }
 
             // Set the Valuetype used during model building
             mpi.buildValueType = mpi.verificationValueType;