Initialiazing var foo: vec4f = vec4() fails with "type can't be inferred"

[andyleiserson]

This failure is from https://martinlaxenaire.github.io/gpu-curtains/examples/shadow-mapping/ via https://bugzilla.mozilla.org/show_bug.cgi?id=1876519, although I think I also hit this problem writing test cases for an unrelated issue.

Shader 'Mesh 0 material render pipeline: fragment shader module' parsing error: type can't be inferred
    ┌─ wgsl:525:28
    │
525 │   var outputColor: vec4f = vec4();
    │                            ^^^^ type can't be inferred

[ErichDonGubler]

Self-contained example:

@compute @workgroup_size(1, 1)
fn main() {
  var bruh: vec3u = vec3();
}