analyze/invalid-fn

This happens when an fn form has an invalid overall shape. Malformed arities can trigger it. Duplicate arities can trigger it too. Invalid variadic usage can also trigger it.

Mitigations

Rewrite the function so each arity has a valid parameter vector and body. If you use a variadic arity, make sure it is well formed. fn comes in two forms.

Single arity

(fn foo [a1 a2]
  (println a1 a2))

Multi-arity

(fn foo
  ([a1]
   (println a1))
  ([a1 a2]
   (println a1 a2)))