Fix vivify() crash in NonStrict methods for read-only scalars

This fixes the crash 'Modification of a read-only value attempted'
when using symbolic references like ${"\!"}{ENOENT}.

For RuntimeScalarReadOnly (immutable scalars), lvalue is null.
When NonStrict methods are called, we now delegate to super
instead of calling vivify(), which allows symbolic references
to work without trying to modify read-only values.

Result: magic.t now passes 158/208 tests (was crashing at 103)

Known issue: Double symbolic dereference like ${"foo"}{key}
still returns empty. This needs further investigation.

Author: fglock

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

@@ -201,33 +201,51 @@ public RuntimeScalar hashDerefExists(RuntimeScalar index) {
     }
 
     // Non-strict versions (allow symbolic references)
+    // Note: We don't call vivify() here because for symbolic references (STRING/BYTE_STRING),
+    // we're not modifying the scalar - we're just using its string value to look up a global variable.
+    // For RuntimeScalarReadOnly (immutable scalars like string literals), lvalue is null and we can't vivify.
+    // Instead, we call the method directly on 'this' which will handle symbolic references correctly.
     public RuntimeScalar hashDerefGetNonStrict(RuntimeScalar index, String currentPackage) {
-        vivify();
+        if (lvalue == null) {
+            // For read-only scalars, call the method on 'this' directly
+            // This will use the RuntimeScalar implementation which handles symbolic references
+            return super.hashDerefGetNonStrict(index, currentPackage);
+        }
         return lvalue.hashDerefGetNonStrict(index, currentPackage);
     }
 
     public RuntimeScalar hashDerefDeleteNonStrict(RuntimeScalar index, String currentPackage) {
-        vivify();
+        if (lvalue == null) {
+            return super.hashDerefDeleteNonStrict(index, currentPackage);
+        }
         return lvalue.hashDerefDeleteNonStrict(index, currentPackage);
     }
 
     public RuntimeScalar hashDerefExistsNonStrict(RuntimeScalar index, String currentPackage) {
-        vivify();
+        if (lvalue == null) {
+            return super.hashDerefExistsNonStrict(index, currentPackage);
+        }
         return lvalue.hashDerefExistsNonStrict(index, currentPackage);
     }
 
     public RuntimeScalar arrayDerefGetNonStrict(RuntimeScalar index, String currentPackage) {
-        vivify();
+        if (lvalue == null) {
+            return super.arrayDerefGetNonStrict(index, currentPackage);
+        }
         return lvalue.arrayDerefGetNonStrict(index, currentPackage);
     }
 
     public RuntimeScalar arrayDerefDeleteNonStrict(RuntimeScalar index, String currentPackage) {
-        vivify();
+        if (lvalue == null) {
+            return super.arrayDerefDeleteNonStrict(index, currentPackage);
+        }
         return lvalue.arrayDerefDeleteNonStrict(index, currentPackage);
     }
 
     public RuntimeScalar arrayDerefExistsNonStrict(RuntimeScalar index, String currentPackage) {
-        vivify();
+        if (lvalue == null) {
+            return super.arrayDerefExistsNonStrict(index, currentPackage);
+        }
         return lvalue.arrayDerefExistsNonStrict(index, currentPackage);
     }