Make sure that a variable that references an enum has to be initialized.

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -216,6 +216,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       variableDeclaration = new VariableDeclaration(variableName, (Expression) expression);
       variableDeclaration.initialized = true;
     } else {
+      if (enumDefs.containsKey(declaredType.getName())) {
+        var error = "Variable " + variableName + " references an enum but is not initialized.";
+        throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+      }
+
       variableDeclaration = new VariableDeclaration(variableName);
     }