Lexer is too permissive with numbers followed by an identifier (e.g. "1foo")

Summary

GHC's lexer lexes numbers followed by an identifier as two separate tokens (number and then identifier) when I think it should reject this as invalid.

Steps to reproduce

GHCi, version 9.8.1: https://www.haskell.org/ghc/  :? for help
ghci> foo = 1
ghci> (+) 1foo
2

Expected behavior

I would expect the lexer to throw an error.

Environment

GHC version used: 9.8.1

Optional:

Operating System:
System Architecture:

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information