Fix source code not being shown in :type errors

src/main/java/de/prob2/jupyter/commands/TypeCommand.java

@@ -68,12 +68,14 @@ public final class TypeCommand implements Command {
 		final ProBKernel kernel = this.kernelProvider.get();
 		final Trace trace = this.animationSelector.getCurrentTrace();
 		final IEvalElement formula = kernel.parseFormula(args.get(FORMULA_PARAM), FormulaExpand.EXPAND);
+		return CommandUtils.withSourceCode(formula, () -> {
 			final TypeCheckResult result = trace.getStateSpace().typeCheck(formula);
 			if (result.isOk()) {
 				return new DisplayData(result.getType());
 			} else {
 				throw new ProBError("Type errors in formula", result.getErrors());
 			}
+		});
 	}
 	
 	@Override