### Patch 1: Check for NULL before assertion
```c
if (str == NULL) {
    // Handle NULL pointer error
    SetLastError(ERROR_INVALID_PARAMETER);
    return -1;
}
WINPR_ASSERT(str);
```

### Patch 2: Remove assertion and add explicit NULL check
```c
if (str == NULL) {
    // Handle NULL pointer error
    SetLastError(ERROR_INVALID_PARAMETER);
    return -1;
}
// Remove WINPR_ASSERT(str) as it's not necessary with explicit check
```

### Patch 3: Use a safer assertion macro
```c
#define SAFE_ASSERT(condition) if (!(condition)) { SetLastError(ERROR_INVALID_PARAMETER); return -1; }
SAFE_ASSERT(str != NULL);
```

### Patch 4: Check for NULL and return an error code
```c
if (str == NULL) {
    // Return an error code instead of asserting
    return -1;
}
// Rest of the function remains the same
```

### Patch 5: Use a try-catch block to handle NULL pointer exception
```c
try {
    if (str == NULL) {
        throw std::invalid_argument("NULL pointer exception");
    }
    // Rest of the function remains the same
} catch (const std::exception& e) {
    // Handle the exception
    SetLastError(ERROR_INVALID_PARAMETER);
    return -1;
}
```

Note: The above patches assume that the `SetLastError` function is used to set the last error code, and `ERROR_INVALID_PARAMETER` is the error code for invalid parameters. The actual error code and handling may vary depending on the specific use case and requirements.