There is, unfortunately, always a risk of world/chunk errors or corruption happening on any server - even Vanilla, though it is much less likely compared to a modded setup. Every single server tick has a very small chance to error and cause problems - every plant growth, mob spawn/despawn, redstone activation, tnt explosion etc... - which is why mods increase the chances as they edit these functions in ways that the server does not always expect, and with multiple mods installed it can cause conflicts which increases the chances further (and add bugs/issues from the mods themselves ontop of the bugs/issues Forge/Fabric etc... have, ontop of the bugs/issues Vanilla has...).
So - while it is a rare occurence - it should always be prepared for as best as possible. It is primarily for this reason that it is highly recommended to make backups of your world(s) regularly, so if this does ever happen you can roll your world back to before it did, as without backups there is rarely any way to fix the problem.
Chunk/world errors and corruption can cause a multitude of problems for your server if/when they happen - this could be as mild as lag issues or glitches when a player is in the area that the corruption chunk or world error is, as that area is then loaded in and actively causing problems, to crashing the server on startup when the world is loaded in. There is also no definite way to be sure that world/chunk errors or corruption has happened in all cases - it does not always crash the server or give errors in the console to suggest this as the problem so it can sometimes be hard to troubleshoot the cause of your issue. The support team may be able to point you in the right direction if you open a ticket regarding your issue - just make sure to include as much information as possible (what the issue is, when it happens, if there are any errors in the server console when it happens, if you changed anything recently etc...).
Fixing World/Chunk Errors or Corruption
Unfortunately there is no simple fix for a world that has errored or has been corrupted.
If you have a backup available from before the problem started then restoring the backup would resolve the issue - make sure that the server has been shut down and the current world folder deleted in full (or renamed if you wish to keep it temporarily just in case) before restoring/uploading the backup you wish to try. If the errored/corrupted world is not fully removed first then the backup will not overwrite the files correctly and the issue will very likely still be present.
The backup must also have been created before the issue happened - if it was not then it will not resolve the issue.
Without usable backups the options become far more destructive - the only definite fixes without backups are to either delete the region file that the chunk/world errors are saved to (this is only possible if the crash reports give a clear indication of which region file is the problem) or to delete the world in full and start from scratch.
In some cases - often on modded setups - the cause is a specific block/mob/item in the world. If this is the case. and you are able to get onto the server and to where the problem block/mob/item is without it crashing then removing them may also resolve the issue. If the issue is a specific modded block, do not replace it once removed - it will cause the same issue again.
For older versions of Minecraft you may also be able to download the world and load it via the program MCEdit and run a repair through this (or delete specific blocks - or chunks - through this if you were unable to get to them ingame), but newer versions of Minecraft may not be compatible due to the many changes in world formatting in each recent major release.
There is also a chunk fixer we can run from our end on request through the tickets - however this is not guaranteed to work (particularly on newer Minecraft versions), and with modded worlds it can cause further damage as it may cause modded blocks/items to be removed from the world as they won't be recognised by the chunk fixer. If you wish for us to try this please shut the server down before opening the ticket and do not touch the server until we have replied to state that the attempted repair has been ran (it is also recommended to download a copy of the world folder before opening the ticket - just in case).
Causes of World/Chunk Errors or Corruption
Unfortunately there is no way to list all possible causes. As stated above, every single server tick can error and cause problems with your world - and due to this there is no way to avoid this happening. It is something that is always a potential risk, though it is a very rare occurence.
The only common cause of world/chunk errors or corruption you can actively avoid is leaving the server running with no free disk space available to save changes to - as with any computer, if the hard drive allocation maxes out things will start to error. You can read up on ways to avoid this and how to have more space allocated if required here: Service Disk Space Information