fix[ux]: improve initializer hint for unimported modules

[charles-cooper]

What I did

fix #4092

How I did it

How to verify it

Commit message

improve initializer hint in the case that the needed module is not
already imported

Description for the changelog

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[cyberthirst]

can't we hint where the import should be performed?

[charles-cooper]

can't we hint where the import should be performed?

you mean at the top of the file?

[cyberthirst]

can't we hint where the import should be performed?

you mean at the top of the file?

i meant into which module:

Error compiling: tests/custom/test4.vy
vyper.exceptions.InitializerException: `lib2` uses `lib1`, but it is not initialized with `lib1`

  (hint: try importing `lib1` first (located at `tests/custom/lib1.vy`))

  contract "tests/custom/lib3.vy:3", line 3:0 
       2
  ---> 3 initializes: lib2
  -------^

here we have an error for test4, initialization happens in lib3, it is said lib2 uses something.. lot of modules are mentioned - it might not be immediately obvious where to insert the import

[charles-cooper]

can't we hint where the import should be performed?

you mean at the top of the file?

i meant into which module:

Error compiling: tests/custom/test4.vy
vyper.exceptions.InitializerException: `lib2` uses `lib1`, but it is not initialized with `lib1`

  (hint: try importing `lib1` first (located at `tests/custom/lib1.vy`))

  contract "tests/custom/lib3.vy:3", line 3:0 
       2
  ---> 3 initializes: lib2
  -------^

here we have an error for test4, initialization happens in lib3, it is said lib2 uses something.. lot of modules are mentioned - it might not be immediately obvious where to insert the import

from offline discussion -- might be nice to have the hint below the source traceback, probably out of scope / should be a new PR though