Enforce promote_type rather than evaluating op

Author: MilesCranmer

src/symbolic_dimensions.jl

@@ -164,7 +164,7 @@ end
 function map_dimensions(op::O, l::SymbolicDimensions{L}, r::SymbolicDimensions{R}) where {O<:Function,L,R}
     zero_L = zero(L)
     zero_R = zero(R)
-    T = typeof(op(zero(L), zero(R)))
+    T = promote_type(L, R)
     I = Vector{INDEX_TYPE}(undef, 0)
     V = Vector{T}(undef, 0)
     nzdims_l = getfield(l, :nzdims)