[Bug]: spoon.support.SpoonClassNotFoundException: cannot load class

### Describe the bug

When I use the `partiallyEvaluate()` method to evaluate a expression, the exception occurs.
The test code is project arthas from [arthas](https://github.com/alibaba/arthas).

When the expression is `(obj.getClass() != com.taobao.arthas.core.env.convert.ConvertiblePair.class)`, spoon can not load the class `com.taobao.arthas.core.env.convert.ConvertiblePair`.

### Source code you are trying to analyze/transform

```Java
(obj.getClass() != com.taobao.arthas.core.env.convert.ConvertiblePair.class)
```

### Source code for your Spoon processing

```Java
expr.partiallyEvaluate();
```

### Actual output

```Java
spoon.support.SpoonClassNotFoundException: cannot load class: com.taobao.arthas.core.env.convert.ConvertiblePair
at spoon.support.reflect.reference.CtTypeReferenceImpl.loadClassWithQName(CtTypeReferenceImpl.java:190)
at spoon.support.reflect.reference.CtTypeReferenceImpl.lambda$getClassFromThreadLocalCacheOrLoad$1(CtTypeReferenceImpl.java:172)
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1133)
at spoon.support.reflect.reference.CtTypeReferenceImpl.getClassFromThreadLocalCacheOrLoad(CtTypeReferenceImpl.java:172)
at spoon.support.reflect.reference.CtTypeReferenceImpl.findClass(CtTypeReferenceImpl.java:163)
at java.base/java.util.Optional.orElseGet(Optional.java:369)
at spoon.support.reflect.reference.CtTypeReferenceImpl.getActualClass(CtTypeReferenceImpl.java:119)
at spoon.support.reflect.eval.VisitorPartialEvaluator.visitFieldAccess(VisitorPartialEvaluator.java:306)
at spoon.support.reflect.eval.VisitorPartialEvaluator.visitCtFieldRead(VisitorPartialEvaluator.java:296)
at spoon.support.reflect.code.CtFieldReadImpl.accept(CtFieldReadImpl.java:18)
at spoon.support.reflect.eval.VisitorPartialEvaluator.evaluate
```

### Expected output

_No response_

### Spoon Version

10.2.1

### JVM Version

11

### What operating system are you using?

windows 11

Start by reproducing expr.partiallyEvaluate() with the reported Arthas expression and inspect VisitorPartialEvaluator.java and CtTypeReferenceImpl.java at the stack-trace locations. The report has no expected output, so clarify the intended handling of the unresolved ConvertiblePair class before defining completion and a regression check.

Written by the indexing model from the issue text.