Improve backslash operator context handling and RuntimeList.createReference

- Detect function calls (BinaryOperatorNode with '(') and use SCALAR context
- This fixes \PVBM where PVBM is a constant sub
- Implement RuntimeList.createReference() for single-element lists
- Preserve LIST context for arrays/hashes to fix tie regression

Author: fglock

src/main/java/org/perlonjava/codegen/EmitOperator.java

@@ -893,7 +893,20 @@ static void handleCreateReference(EmitterVisitor emitterVisitor, OperatorNode no
                     node.operand.accept(emitterVisitor.with(RuntimeContextType.LIST));
                 }
             } else {
-                node.operand.accept(emitterVisitor.with(RuntimeContextType.LIST));
+                // Determine context based on operand type
+                // Function calls and scalar expressions should use SCALAR context
+                // Arrays, hashes, and lists should use LIST context
+                int contextType = RuntimeContextType.LIST;
+                
+                if (node.operand instanceof BinaryOperatorNode binOp && binOp.operator.equals("(")) {
+                    // Function call - use SCALAR context to get single return value
+                    contextType = RuntimeContextType.SCALAR;
+                } else if (node.operand instanceof OperatorNode op && op.operator.equals("$")) {
+                    // Scalar variable - use SCALAR context
+                    contextType = RuntimeContextType.SCALAR;
+                }
+                
+                node.operand.accept(emitterVisitor.with(contextType));
                 emitterVisitor.ctx.mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL,
                         "org/perlonjava/runtime/RuntimeBase",
                         "createReference",

src/main/java/org/perlonjava/runtime/RuntimeList.java

@@ -324,13 +324,20 @@ public RuntimeScalar scalar() {
     }
 
     /**
-     * Throws an exception as creating a reference of a list is not implemented.
+     * Creates a reference from a list.
+     * For single-element lists (e.g., from constant subs), creates a reference to that element.
+     * For empty or multi-element lists, this is an error in scalar context.
      *
-     * @throws PerlCompilerException Always thrown as creating a reference is not implemented.
+     * @return A RuntimeScalar reference to the list element
+     * @throws PerlCompilerException if the list doesn't contain exactly one element
      */
     public RuntimeScalar createReference() {
-        // TODO
-        throw new PerlCompilerException("TODO - create reference of list not implemented");
+        if (elements.size() == 1) {
+            // Single element list - create reference to that element
+            return elements.get(0).scalar().createReference();
+        }
+        // Empty or multi-element list in reference context is an error
+        throw new PerlCompilerException("Can't create reference to list with " + elements.size() + " elements");
     }
 
     /**