['Entity with index' errors during travel through sectors]

I'm seeing the following errors on a dedicated server (either Windows or Linux, it's the same) log:

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2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '8'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '9'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '10'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '12'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '13'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '14'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '15'.
2024-03-26 07-17-13| Entity with index eb001b32-fd54-47fa-aa12-8b0f540737bf has no script number '17'.
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The server runs well enough in general, but these errors are typically followed by a:

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2024-03-26 07-24-14| Warning: Sector (-xxx:yyy) had a very long tick of over 4278ms.
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or similar.  In general, what causes these "Entity with index .. has no script number ... " errors?