fix GG scoping for scalar build_function

Author: isaacsas

src/build_function.jl

@@ -114,7 +114,7 @@ function _build_function(target::JuliaTarget, op::Operation, args...;
 
     fname = gensym(:ModelingToolkitFunction)
     out_expr = conv(op)
-    let_expr = Expr(:let, var_eqs, out_expr)
+    let_expr = Expr(:let, var_eqs, Expr(:block, out_expr))
     bounds_block = checkbounds ? let_expr : :(@inbounds begin $let_expr end)
 
     fargs = Expr(:tuple,argnames...)

test/reactionsystem.jl

@@ -123,7 +123,6 @@ for i = 1:14
   @test jumps[i].net_stoch == maj.net_stoch
 end
 for i = 15:18
-  (i==16) && continue
   crj = MT.assemble_crj(js, js.eqs[i], statetoid)
   @test isapprox(crj.rate(u0,p,time), jumps[i].rate(u0,p,time))
   fake_integrator1 = (u=zeros(4),p=p,t=0); fake_integrator2 = deepcopy(fake_integrator1);