what are the dangers of transfering bitcoins between addresses? So I heard stories about people losing bitcoins because their wallet didn't support a cerain feature.. or bitcoins getting sent to wrong address etc.. how does that happen?
As a software developer I'll be using bitcoin in my application for payments.
What should I be looking for? security wise..
I see that sending between legacy and segwit addresses is not a problem...
The dangers are minimal.

There is no restriction on which addresses can send to which other addresses.

Most common issues arise from wallets failing to support different address encodings (many wallets still do not support bech32), which results in them rejecting valid addresses.

Other, rarer, issues include mixing up address types - a few wallets in the past have interpreted p2sh addresses as p2pkh addresses and sent coins to the correct HASH160 value embedded in an incorrect locking script, effectively burning them.