Error when running `saga:wetnessindex`

[pat-s]

I was just trying to execute some algs after having a working ´find_algorithms()` again and faced the following error.

data("dem", package = "RQGIS3")

find_algorithms("wetness")
alg <- "saga:sagawetnessindex"

twi <- run_qgis(alg,
+   DEM = dem,
+   TWI = file.path(tempdir(), "twi.asc"),
+   load_output = TRUE
+ )
../src/core/qgsmessagelog.cpp:29 : (logMessage) [68494ms] 2019-12-02T23:27:18 [1] Invalid data provider gdal
../src/core/qgsmessagelog.cpp:29 : (logMessage) [1ms] 2019-12-02T23:27:18 Processing[2] Unable to execute algorithm
Could not load source layer for DEM: /private/var/folders/w5/1wdhg7nd4zj7td7_pkgrl4fm0000gn/T/Rtmp61xW7L/file1749219175544.tif not found
Error in py_call_impl(callable, dots$args, dots$keywords) : 
  QgsProcessingException: Unable to execute algorithm
Could not load source layer for DEM: /private/var/folders/w5/1wdhg7nd4zj7td7_pkgrl4fm0000gn/T/Rtmp61xW7L/file1749219175544.tif not found

Detailed traceback: 
  File "/usr/local/Cellar/osgeo-qgis/3.8.0_1/QGIS.app/Contents/Resources/python/plugins/processing/tools/general.py", line 106, in run
    return Processing.runAlgorithm(algOrName, parameters, onFinish, feedback, context)
  File "/usr/local/Cellar/osgeo-qgis/3.8.0_1/QGIS.app/Contents/Resources/python/plugins/processing/core/Processing.py", line 137, in runAlgorithm
    raise QgsProcessingException(msg)