"Weights sum to zero, can't be normalized" Error

[JinIgarashi]

Because of this error, RCA tool does not work now

Reproduce

• localhsot http://localhost:8000/cog/statistics?url=https://titiler-dev.undpgeohub.org/vrt?url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F09%252FSVDNB_npp_d20230909.rade9d_sunfiltered.tif%26url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F15%252FSVDNB_npp_d20230915.rade9d_sunfiltered.tif%26url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F09%252FSVDNB_npp_d20230909.vcld.tif%26url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F15%252FSVDNB_npp_d20230915.vcld.tif&algorithm=rca&histogram_bins=8

• dev https://titiler-dev.undpgeohub.org/cog/statistics?url=https%3A%2F%2Ftitiler-dev.undpgeohub.org%2Fvrt%3Furl%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F09%252FSVDNB_npp_d20230909.rade9d_sunfiltered.tif%26url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F15%252FSVDNB_npp_d20230915.rade9d_sunfiltered.tif%26url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F09%252FSVDNB_npp_d20230909.vcld.tif%26url%3Dhttps%253A%252F%252Fundpgeohub.blob.core.windows.net%252Fstacdata%252Fnighttime-lights%252F2023%252F09%252F15%252FSVDNB_npp_d20230915.vcld.tif&algorithm=rca&histogram_bins=8

[JinIgarashi]

If I comment the following code, statistics api can work.

https://github.com/UNDP-Data/geo-cogserver/blob/3c7790325749ec8525f2958586783df81c0c4395/src/cogserver/algorithms/rca.py#L82-L83