Let's analyze the code step by step to identify the potential CWE-476 (NULL Pointer Dereference) vulnerability:

1. Input analysis:
   - The function takes `func_obj_p` as an input parameter of type `ecma_object_t *`.
   - `func_obj_p` is a pointer to a function object.

2. Vulnerability check:
   - Line 7 contains an assertion: `JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));`
   - This assertion checks two conditions:
     a) `func_obj_p` is not NULL
     b) `func_obj_p` is not a lexical environment

3. Potential issue:
   - The assertion is used to check if `func_obj_p` is NULL, which is good practice.
   - However, assertions are often disabled in release builds for performance reasons.

4. Vulnerability explanation:
   - If the assertion is disabled (e.g., in a release build), and `func_obj_p` is NULL, the function will continue execution without this check.
   - This could lead to a NULL pointer dereference later in the function when `func_obj_p` is used, particularly in the switch statement at line 20: `switch (ecma_get_object_type (func_obj_p))`

5. Consequences:
   - If `func_obj_p` is NULL and the assertion is disabled, calling `ecma_get_object_type(func_obj_p)` will result in a NULL pointer dereference.
   - This can cause a program crash or potentially be exploited for malicious purposes.

Conclusion:
The vulnerability lies in relying solely on an assertion to check for NULL pointers. While assertions are useful for debugging, they should not be the only safeguard against NULL pointer dereferences. A proper NULL check should be implemented that remains active in all build configurations to ensure the function handles NULL inputs safely.