Bug: `json.decode()` returns internal 'any' type that users cannot use

[SchoolyB]

Description

json.decode() without a type argument returns (any, error), but any is an internal-only type that users cannot declare or work with.

temp result, err = json.decode(jsonString)
// result has type 'any' - but what can the user do with it?

The user cannot:

• Declare a variable as any: temp x any = ... is not allowed
• Pass it to a function expecting a concrete type
• Use it meaningfully without casting

Affected Functions

From pkg/typechecker/typechecker.go:4947-4956:

case "decode":
    if len(args) >= 2 {
        if label, ok := args[1].(*ast.Label); ok {
            return []string{label.Value, "error"}
        }
    }
    return []string{"any", "error"}  // ← Problem
case "parse", "parse_file":
    return []string{"any", "error"}  // ← Same problem

Expected Behavior

Either:

1. Require a type argument: json.decode(text, MyType) - no untyped version
2. Return a usable dynamic type that users can work with
3. Document a pattern for working with untyped JSON (if one exists)

Current Workaround

Always provide a type argument:

temp result, err = json.decode(jsonString, MyStruct)

But if users don't know the type at compile time, they're stuck.