defmodule Customer do
  defstruct name: "", company: ""
end

defmodule BugReport do
  defstruct owner: %Customer{}, details: ""
end

report = %BugReport{
  owner: %Customer{name: "Dave", company: "PragProg"},  # this is line 10, error line  
  details: "broken"
}

  error: cannot access struct Customer, the struct was not yet defined or the struct is being accessed in the same context that defines it
    │
 10 │   owner: %Customer{name: "Dave", company: "PragProg"},
    │          ^
    │
    └─ nested_dict_api.exs:10:10

** (CompileError) nested_dict_api.exs: cannot compile file (errors have been logged)

NOTE, this is when i put all my modules in one file.

#Customer.exs
defmodule Customer do
  defstruct name: "", company: ""
end

#nested_dict_api.exs
Code.require_file("Customer.exs")

defmodule BugReport do
  defstruct owner: %Customer{}, details: ""
end

#nested_dict.exs
Code.require_file("nested_dict_api.exs")
Code.require_file("Customer.exs")

report = %BugReport{
  owner: %Customer{name: "Dave", company: "PragProg"},   #error is here on line, line 5 
  details: "broken"
}

IO.inspect(report)

error

    error: Customer.__struct__/1 is undefined, cannot expand struct Customer. Make sure the struct name is correct. If the struct name exists and is 
correct but it still cannot be found, you likely have cyclic module usage in your code
    │
  5 │   owner: %Customer{name: "Dave", company: "PragProg"},
    │          ^
    │
    └─ nested_dict.exs:5:10

** (CompileError) nested_dict.exs: cannot compile file (errors have been logged)

Both method WORK ON iex but not on elixir <filename>.exs command