Avoid error with MATLAB classes that we can't handle

Author: jebej

src/MAT_HDF5.jl

@@ -169,6 +169,9 @@ function m_read(dset::HDF5Dataset)
             end
         end
         return out
+    elseif !haskey(str2type_matlab,mattype)
+        @warn "MATLAB $mattype values are currently not supported"
+        return missing
     end
 
     # Regular arrays of values