Step 1:  root cause of the CWE-476 (NULL Pointer Dereference) vulnerability in this code slice is:

The JERRY_ASSERT macro on line 7 attempts to dereference the func_obj_p pointer without first ensuring it is not NULL. While the assertion does check if func_obj_p is NULL, it does so in a compound condition that can lead to a NULL pointer dereference if func_obj_p is indeed NULL.

Specifically:

1. The assertion uses a logical AND (&&) operator to combine two conditions.
2. The first condition checks if func_obj_p is not NULL.
3. However, if func_obj_p is NULL, the second part of the condition (!ecma_is_lexical_environment(func_obj_p)) will still be evaluated due to the nature of the && operator.
4. This evaluation will attempt to dereference func_obj_p by passing it to the ecma_is_lexical_environment function, even though it's NULL.

This can lead to a NULL pointer dereference if func_obj_p is NULL, potentially causing a program crash or undefined behavior.

To fix this, the assertion should be split into two separate checks:

```c
JERRY_ASSERT (func_obj_p != NULL);
JERRY_ASSERT (!ecma_is_lexical_environment (func_obj_p));
```

This way, the second assertion will only be evaluated if func_obj_p is not NULL, preventing the potential NULL pointer dereference.
Based on the root cause analysis, here are five possible patches to address the CWE-476 vulnerability in the given code:

Patch 1: Split the assertion into two separate checks
```diff
- JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+ JERRY_ASSERT (func_obj_p != NULL);
+ JERRY_ASSERT (!ecma_is_lexical_environment (func_obj_p));
```

Patch 2: Use a conditional statement to check for NULL before calling the function
```diff
- JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+ JERRY_ASSERT (func_obj_p != NULL);
+ if (func_obj_p != NULL)
+ {
+     JERRY_ASSERT (!ecma_is_lexical_environment (func_obj_p));
+ }
```

Patch 3: Use a ternary operator to avoid calling the function if func_obj_p is NULL
```diff
- JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+ JERRY_ASSERT (func_obj_p != NULL && (func_obj_p == NULL ? true : !ecma_is_lexical_environment (func_obj_p)));
```

Patch 4: Replace the assertion with a runtime check that returns an error
```diff
- JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+ if (func_obj_p == NULL || ecma_is_lexical_environment (func_obj_p))
+ {
+     return ecma_raise_type_error (ECMA_ERR_INVALID_FUNCTION_OBJECT);
+ }
```

Patch 5: Use a macro to safely check the condition
```diff
+ #define SAFE_CHECK(ptr, func) ((ptr) != NULL && !(func)(ptr))
- JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+ JERRY_ASSERT (SAFE_CHECK(func_obj_p, ecma_is_lexical_environment));
```

Each of these patches addresses the vulnerability in a slightly different way, offering various trade-offs between code clarity, performance, and error handling. The choice of which patch to use would depend on the specific requirements and coding standards of the project.