I can't figure out why this returns an error yet these are the values I need to work with.
library(terra)
#> terra 1.7.78
r1 <- rast(ncols=10, nrows=10, nlyr=6, vals=0.00:0.56)
r2 <- rast(ncols=10, nrows=10, nlyr=6, vals=0.00000000:0.03338733)
r3 <- weighted.mean(r1, r2, na.rm=TRUE)
Since all your weights are zero, weighted means cannot be computed. With more sensible weights this appears to work:
library(terra)
set.seed(1)
r1 <- rast(ncols=10, nrows=10, nlyr=6, vals=sample(10, 600, replace=TRUE))
r2 <- rast(ncols=10, nrows=10, nlyr=6, vals=sample(10, 600, replace=TRUE))
r3 <- weighted.mean(r1, r2, na.rm=TRUE)
r3
#class : SpatRaster
#dimensions : 10, 10, 1 (nrow, ncol, nlyr)
#resolution : 36, 18 (x, y)
#extent : -180, 180, -90, 90 (xmin, xmax, ymin, ymax)
#coord. ref. : lon/lat WGS 84 (CRS84) (OGC:CRS84)
#source(s) : memory
#name : sum
#min value : 2.214286
#max value : 8.481481