fixup! fix: handle => nothing entries in u0map in generate_initializesystem

Author: AayushSabharwal

src/systems/nonlinear/initializesystem.jl

@@ -32,6 +32,7 @@ function generate_initializesystem(sys::AbstractSystem;
 
     # PREPROCESSING
     # If `=> nothing` in `u0map`, remove the key from `defs`
+    u0map = copy(anydict(u0map))
     for (k, v) in u0map
         v === nothing || continue
         delete!(defs, k)
@@ -44,7 +45,6 @@ function generate_initializesystem(sys::AbstractSystem;
     # map parameters in `initprob` which need to be updated in `update_initializeprob!`
     # to the corresponding expressions that determine their values
     new_params = Dict()
-    u0map = copy(anydict(u0map))
     pmap = copy(anydict(pmap))
     if is_time_dependent(sys)
         for (k, v) in u0map