remove loading fallback

Author: IanButterworth

base/loading.jl

@@ -960,9 +960,6 @@ end
 # require always works in Main scope and loads files from node 1
 const toplevel_load = Ref(true)
 
-const full_warning_showed = Ref(false)
-const modules_warned_for = Set{PkgId}()
-
 """
     require(into::Module, module::Symbol)
 
@@ -1008,28 +1005,14 @@ function require(into::Module, mod::Symbol)
                     Package $mod not found in current path$hint_message.
                     - $start_sentence `import Pkg; Pkg.add($(repr(String(mod))))` to install the $mod package."""))
             else
-                s = """
+                throw(ArgumentError("""
                 Package $(where.name) does not have $mod in its dependencies:
                 - You may have a partially installed environment. Try `Pkg.instantiate()`
                   to ensure all packages in the environment are installed.
                 - Or, if you have $(where.name) checked out for development and have
                   added $mod as a dependency but haven't updated your primary
                   environment's manifest file, try `Pkg.resolve()`.
-                - Otherwise you may need to report an issue with $(where.name)"""
-
-                uuidkey = identify_package(PkgId(string(into)), String(mod))
-                uuidkey === nothing && throw(ArgumentError(s))
-
-                # fall back to toplevel loading with a warning
-                if !(where in modules_warned_for)
-                    @warn string(
-                        full_warning_showed[] ? "" : s, "\n",
-                        string("Loading $(mod) into $(where.name) from project dependency, ",
-                               "future warnings for $(where.name) are suppressed.")
-                    ) _module = nothing _file = nothing _group = nothing
-                    push!(modules_warned_for, where)
-                end
-                full_warning_showed[] = true
+                - Otherwise you may need to report an issue with $(where.name)"""))
             end
         end
         if _track_dependencies[]