[Vala] How to check if string is empty

[Alexandre Oliveira <xinayder airmail cc>]

Hello!

I've just heard about Vala and I've been messing around with it these
past days.

However, I came across a problem. I need to check if some strings aren't
empty, and I realized there's no method in Vala that's equivalent to
C#'s `string.IsNullOrEmpty(string)`.

I tried setting up a static method to check if the given string is empty:
```
static bool is_empty(string str) {
    return str[0] == '\0' || str == null;
}
```

However, running my code, I get the following message repeatedly in my
terminal: ** (main.exe:2288): CRITICAL **: is_empty: assertion 'str !=
NULL' failed

What am I doing wrong?

Thanks!
-- 
Alexandre Oliveira
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