Step 1: 's analyze the code step by step to identify the potential vulnerability:

1. Input:
   - The function takes `func_obj_p` as an input parameter, which is a pointer to a function object.

2. Line 7:
   - There's an assertion checking that `func_obj_p` is not NULL and not a lexical environment.
   - This check helps prevent null pointer dereferences, which is good practice.

3. Line 20:
   - The code uses `ecma_get_object_type(func_obj_p)` in a switch statement.

4. Vulnerability analysis:
   - The assertion on line 7 checks for NULL, but it's only an assertion.
   - In release builds, assertions are often disabled, meaning this check might not exist in production code.
   - There's no explicit NULL check between the assertion and the use of `func_obj_p` on line 20.

5. Potential vulnerability:
   - If `func_obj_p` is NULL and the assertion is disabled or removed, line 20 would attempt to dereference a NULL pointer.
   - This situation matches CWE-476: NULL Pointer Dereference.

6. Impact:
   - A NULL pointer dereference can lead to a program crash or potential exploitation in some cases.

Conclusion:
The vulnerability in this code is likely CWE-476 (NULL Pointer Dereference). While there's an assertion check, relying solely on assertions for NULL checks is not sufficient, especially in production code where assertions might be disabled. The code should include an explicit NULL check before using `func_obj_p` on line 20 to ensure robust error handling and prevent potential crashes or security issues.
Based on the analysis, here are five possible patches to address the CWE-476 (NULL Pointer Dereference) vulnerability:

Patch 1: Add an explicit NULL check with error return
```diff
7   JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+   if (func_obj_p == NULL)
+   {
+       return ecma_raise_type_error (ECMA_ERR_ARGUMENT_IS_NULL);
+   }
9   ECMA_CHECK_STACK_USAGE ();
```

Patch 2: Use a macro for NULL check that works in all build configurations
```diff
+ #define SAFE_NULL_CHECK(ptr) do { if ((ptr) == NULL) { return ecma_raise_type_error (ECMA_ERR_ARGUMENT_IS_NULL); } } while(0)

7   JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+   SAFE_NULL_CHECK(func_obj_p);
9   ECMA_CHECK_STACK_USAGE ();
```

Patch 3: Add NULL check and use a default case in the switch statement
```diff
7   JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+   if (func_obj_p == NULL)
+   {
+       result = ecma_raise_type_error (ECMA_ERR_ARGUMENT_IS_NULL);
+   }
+   else
+   {
20     switch (ecma_get_object_type (func_obj_p))
    {
      // ... existing cases ...
+     default:
+         result = ecma_raise_type_error (ECMA_ERR_INVALID_OBJECT_TYPE);
+         break;
    }
+   }
```

Patch 4: Use a helper function for type checking and error handling
```diff
+ static ecma_value_t check_function_object(ecma_object_t *obj_p)
+ {
+     if (obj_p == NULL)
+     {
+         return ecma_raise_type_error (ECMA_ERR_ARGUMENT_IS_NULL);
+     }
+     if (ecma_is_lexical_environment (obj_p))
+     {
+         return ecma_raise_type_error (ECMA_ERR_EXPECTED_OBJECT);
+     }
+     return ECMA_VALUE_EMPTY;
+ }

7   JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+   ecma_value_t check_result = check_function_object(func_obj_p);
+   if (ecma_is_value_error(check_result))
+   {
+       return check_result;
+   }
9   ECMA_CHECK_STACK_USAGE ();
```

Patch 5: Use a combination of assertion and runtime check
```diff
7   JERRY_ASSERT (func_obj_p != NULL && !ecma_is_lexical_environment (func_obj_p));
+   #ifndef NDEBUG
+   if (func_obj_p == NULL || ecma_is_lexical_environment (func_obj_p))
+   {
+       return ecma_raise_type_error (ECMA_ERR_INVALID_ARGUMENT);
+   }
+   #endif
9   ECMA_CHECK_STACK_USAGE ();
```

Each of these patches adds an extra layer of protection against NULL pointer dereference, while maintaining the existing functionality. The choice between them would depend on the specific coding standards, error handling practices, and build configurations of the project.