error: failed to build a valid final module: Function [1] 'func' is invalid
  ┌─ tests/error_test/wgsl_valid_err.wgsl:7:1
  │  
7 │ ╭ fn func() -> f32 {
8 │ │     return 1u;
  │ │            ^^ naga::ir::Expression [0]
  │ ╰──────────────^ naga::ir::Function [1]
  │  
  = The `return` expression Some([0]) does not match the declared return type Some([0])

