Learn Croatian: Ako ambalaža nije dobra, bojim se da staklo ne napukne. - If the packaging is not good, I am afraid the glass might crack.

This is exactly what this lesson covers: "empty" or expletive negation. After verbs of fearing like bojati se, Croatian often uses da ne + present tense to express the fear that something might or will happen. The ne here doesn't actually make the verb negative; it just emphasizes the apprehension or warning.

Could I express this same fear without using the empty ne?

Yes! If you don't use the empty ne, you would usually switch to the future tense instead of the present: bojim se da će staklo napuknuti. Both versions mean the same thing, but the da ne + present tense structure used in this sentence feels very natural and immediate to native speakers.

What is the difference between napukne and just pukne?

Both are perfective verbs, but the prefix na- adds the meaning of "partially" or "to a small degree." While puknuti means to completely break, snap, or burst, napuknuti means to just crack or fracture (like a cracked phone screen or a structurally compromised piece of glass).

Is ambalaža the normal word for "packaging", or is it just formal terminology?