constructively break the tests

src/symbolics.jl

@@ -114,7 +114,7 @@ function Base.convert(
     convert_time = (x::SBML.MathTime) -> Num(Variable(Symbol(x.id))).val,
     convert_const = (x::SBML.MathConst) -> Num(default_symbolics_constants[x.id]),
 )
-    conv(x::SBML.MathApply) = eval(allowed_sym(x.fn, mapping))(conv.(x.args)...)
+    conv(x::SBML.MathApply) = Num(eval(allowed_sym(x.fn, mapping))(conv.(x.args)...))
     conv(x::SBML.MathTime) = convert_time(x)
     conv(x::SBML.MathConst) = convert_const(x)
     conv(x::SBML.MathIdent) = Num(Variable(Symbol(x.id))).val